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Tumor Biology |
5-Integrin-negative Teratocarcinomas and Embryoid Bodies1
Howard Hughes Medical Institute and Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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ABSTRACT |
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 Top ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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5-integrin—were injected ectopically into syngeneic mice to develop teratocarcinomas. 5-null-derived teratocarcinomas were significantly smaller than the wild-type or 5 heterozygous tumors. Histological analysis revealed the presence of tissues derived from all three germ layers, in all tumors. However, 5-null teratocarcinomas displayed less undifferentiated tissue than did the controls. Decreased proliferation and increased apoptosis were observed in the undifferentiated areas of the 5-null teratocarcinomas. The expression of extracellular matrix proteins, fibronectin and tenascin-C, and the basement membrane components, laminin, entactin/nidogen, and collagen IV, was similar in the different tumors, although the deposition of these molecules was more disorganized in 5-null teratocarcinomas. The absence of 5-integrin in the various tissues of the 5-null tumors was confirmed by immunohistochemistry. Many vessels, but not all, stained positively for 5-integrin, showing that they were host derived. Analysis of the area occupied by vessels revealed, on average, an 8-fold decrease in 5-null teratocarcinomas compared with control tumors. Staining for smooth muscle -actin showed that pericytes and smooth muscle cells were recruited around the vessels in all tumors, suggesting similar vessel differentiation. Deposition of EIIIA and EIIIB and fibronectin around the vessels was observed in all tumors. The fact that some, although few, 5-integrin-negative vessels existed in 5-null tumors indicated that 5-/- ES cells could differentiate into endothelial cells. Endothelial cell differentiation and vessel formation were analyzed also in vitro. 5-null ES cells were differentiated into embryoid bodies, although they were delayed in growth and attachment. Differentiation into endothelial cells was achieved, but the organization into a complex vasculature was delayed compared with controls. We conclude that 5ß1-integrin plays a significant role in vessel formation both in ES cell cultures and in teratocarcinomas. Reduced vascularization likely contributed to the reduced proliferation and increased apoptosis observed in 5-null teratocarcinomas. |
INTRODUCTION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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and ß subunits. Most cells express many integrins and are, therefore, able to interact with many ECM molecules. Integrins often bind to more than one ligand; however, some show selectivity. For instance, the 5ß1 integrin binds specifically to FN (11)
. 5ß1 integrin is involved in many biological processes including cell proliferation and oncogenic transformation (12, 13, 14)
, embryogenesis (e.g., vasculogenesis; Refs. 10
, 15
, and 16
),4
cell survival (16
, 17)
, cell migration (13
, 18) , and cell spreading (19)
.
A characteristic property of tumor cells is their reduced adhesion to solid substrates. In culture, many transformed cells do not spread and grow as multilayered foci. In some instances, when transplanted into animals, they can invade and colonize different organs. The role of 5-integrin in cellular transformation, tumor formation and/or progression has been studied in vitro and in vivo. In ras-transformed cells, a reduction in the level of 5ß1-integrin was found (12)
. Transformed Chinese hamster ovary (13)
and human colon carcinoma cells (16)
induced to overexpress the 5ß1-integrin lose the potential to form tumors in mice. Studies of osteosarcoma (20
, 21)
and erythroleukemia cells (22)
expressing different levels of 5ß1 show that cells that attach better to FN overexpress 5ß1 and are less tumorigenic. The level of 5ß1 is reduced in many human and murine tumors (23, 24, 25, 26)
. However, we recently took several genetic approaches using mice with targeted mutations in the gene encoding 5-integrin (knock-out or chimeric mice) and found that 5ß1-integrin did not contribute to tumorigenesis or metastasis in the genetic backgrounds studied (27)
.
ES cells, as well as pre- or early postimplantation embryos, can develop into tumors when transplanted into an ectopic location in syngeneic animals (28) . These tumors differentiate into various tissues and are called teratocarcinomas. Genetically manipulated ES cells can be used to generate such tumors (29, 30, 31) and to study the role of specific genes during tissue differentiation and tumor development. Folkman and D’Amore (32) demonstrated that tumor growth is dependent on angiogenesis, i.e., the sprouting of new capillary vessels from preexisting vessels. Teratocarcinomas are also useful systems to study the process of angiogenesis (30 , 33) .
In our study, we injected 5-integrin-null ES cells into syngeneic mice to generate teratocarcinomas. Here we present data on tissue differentiation, proliferation, cell death, ECM deposition, and blood vessel formation of 5-null teratocarcinomas in comparison with controls. Endothelial cell differentiation and vessel formation were also studied in vitro by inducing 5-null ES cells to differentiate into EBs in the presence of growth factors promoting endothelial differentiation.
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MATERIALS AND METHODS |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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5 integrin +/-; Ref. 34
); 154 and 305 (5 integrin -/-; Ref. 34
). ES cells were grown as described (35)
. Differentiation of ES cells was obtained by the hanging drop method as described (36)
. To promote endothelial cell differentiation and vessel formation, the following growth factors were added to the medium: vascular endothelial cell growth factor (Peprotech, Inc., Rocky Hill, NJ; 50 ng/ml); recombinant human basic fibroblast growth factor (Genzyme, Cambridge, MA; 100 ng/ml); recombinant mouse interleukin 6 (Genzyme; 10 ng/ml); erythropoietin (Boehringer-Mannheim, Mannheim, Germany); and insulin (Life Technologies, Inc.; 10 µg/ml).
Immunohistochemistry.
The EBs were fixed with cold methanol for 5 min after 5, 7, or 11 days of adhesion on gelatin-coated coverslips and analyzed for the presence of PECAM, FN, and SMA as described (36)
. Frozen sections (6 µm) from unfixed tumors were processed as described (34)
. The following primary antibodies were used at 1:100 dilution: rat monoclonal anti-PECAM (CD31; PharMingen, San Diego, CA); rabbit polyclonal anti-vWF (Diagnostica Stago, Asniere, France); rabbit 24 polyclonal anti-FN (37)
; mouse monoclonal anti SMA (clone 1A4; Dako, Carpinteria, CA); rabbit polyclonal anti-LM (Sigma Chemical Co.); rat monoclonal anti-TN-C (Mtn-12; Sigma Chemical Co.); goat polyclonal anti-EIIIA-FN (38)
; rabbit polyclonal anti-EIIIB-FN (39)
; rabbit polyclonal anti-entactin/nidogen (a gift of A. Chung, University of Pittsburgh, Pittsburgh, PA); and rat monoclonal anti-5 integrin (PharMingen). The following secondary antibodies were used at 1:200 dilution: FITC-conjugated goat antirabbit or antirat (Biosource International, Camarillo, CA); TRITC-conjugated goat antirabbit or antirat (Biosource International).
Teratocarcinoma Induction.
ES cells (107) were trypsinized, washed twice, resuspended in 100 or 200 µl of PBS, and injected s.c. onto the backs of 8-week-old syngeneic 129/SvJae male mice. After 18, 23, 24, or 25 days, tumors were surgically removed and weighed. A portion was embedded in mounting medium (OCT compound; Miles Laboratories, Elkhart, Milwaukee, WI) and immediately frozen in liquid nitrogen-cooled isopentane. The rest of the tumor was fixed overnight in 10% formalin (3.7% formaldehyde in PBS) and paraffin embedded the day after 6-µm sections were processed for H&E staining.
Cell Proliferation and Apoptosis.
Proliferation was analyzed on frozen sections using an anti-nuclear antigen Ki67 antibody (Novocastra, Newcastle, United Kingdom). Frozen sections were fixed and stained (1:500 dilution) as above. Before mounting the slides, 2 min staining with propidium iodide counterstained the nuclei. Apoptotic cells were analyzed using TUNEL on paraffin sections from formalin-fixed tumors as described (40)
.
Evaluation of Vessel Area.
Frozen sections from WT, 5+/- or 5-/- tumors were stained with an anti-vWF or anti-PECAM antibody to label endothelial cells following the procedure described in the immunohistochemistry paragraph. The area occupied by vessels was evaluated with a microscope connected to a computer, and NIH/SCION image camera software was used to measure the area occupied by vessels present in randomly selected fields (x40). Ten WT and 10 5-/- tumors were measured, and average values were compared. Many more tumors were evaluated by eye.
Statistical Analyses.
Statistical analyses were assessed by the two-tailed student’s t test. P < 0.05 was considered statistically significant.
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RESULTS |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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5-Integrin-Null Teratocarcinomas Are Smaller Than Controls.5-integrin during the development of teratocarcinomas, 5-/-, 5+/-, or WT ES cells were injected s.c. into the backs of syngeneic 129/SvJae male mice. Three independent sets of experiments were performed (Fig. 1)
. Representative mice from the null and WT groups are shown in Fig. 2
. All three experiments showed statistically significant differences between 5-null animals and control ES cells; the 5-null tumors grow more slowly.
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5-/- ES-Cell Derived Teratocarcinomas Differentiate into Ecto-, Endo-, and Mesodermal Tissues and Are 5-negative except for Most of the Blood Vessels.5-null tumors, similar to controls, are composed of ecto-, endo- and mesodermally differentiated tissues. Some examples are shown in Fig. 3
. However, a higher proportion of undifferentiated cells was observed in control tumors. The expression of 5 integrin in the different tissues was analyzed using an antibody against 5-integrin. The 5-null ES cell-derived tumors were negative for 5-integrin in all of the tissues except for a majority of the blood vessels (Fig. 3H)
. The control teratocarcinomas were highly positive for 5 staining (Fig. 3G)
. Negative controls were included in each experiment (data not shown).
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5-Null ES Cell-derived Teratocarcinomas.5-null teratocarcinomas and 5 control tumors by staining the nuclei with the Ki67 nuclear marker. Propidium iodide staining was used to counterstain all nuclei. Ten microscopic fields were counted for each tumor. High proliferation was observed in controls (positive nuclei, 30–40%), mostly in the undifferentiated areas, whereas lower proliferation was observed in 5-null teratomas (positive nuclei, 8–15%; Fig. 4A)
. Histological staining with H&E shows the appearance of highly undifferentiated areas (blue), which are less prevalent in the 5-null tumors.
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5-null and 5 control tumors. Ten microscopic fields were counted for each tumor. Apoptotic cells were differentially distributed in the two groups. Three % to 6% of apoptotic nuclei were found in controls, whereas <1% of the nuclei were apoptotic in 5-/- tumors. However, importantly, in control tumors apoptotic cells were mostly concentrated in areas of nervous tissue, whereas in 5-null tumors, they were mostly found in undifferentiated, proliferative zones (Fig. 4B)
. Thus, reduced proliferation and increased apoptosis in proliferative zones cause slower growth of the 5-null tumors.
5-null tumors show a more disorganized ECM distribution. To test for the deposition of ECM molecules in the absence of 5-integrin, we analyzed the deposition of several ECM proteins in 5-null-ES cell-derived tumors. Tumors were stained for FN and TN-C or for the basement membrane components LM, entactin/nidogen, and collagen IV. Comparison showed that all of these molecules were present in the two groups of tumors, although in 5-null tumors the deposition was more disorganized (Fig. 5)
. Analysis of the basement membrane ultrastructural morphology was also performed with an electron microscope. The basement membranes were continuously present along the basal surface of the cells in both mutant and control tumors (data not shown). It is therefore possible that the general disorganization of ECM observed in 5-null tumors was a consequence of different tissue distribution compared with the controls.
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5-/- ES Cell-derived Teratocarcinomas.5-/- or WT ES cell-derived teratocarcinomas were immunostained for 5-integrin. The same sections were costained with antibodies for endothelial cell markers (anti-PECAM or anti-vWF antibodies) to outline endothelial cells. Representative sections of 5-/- or 5+/+ ES cell-derived tumors, double-stained for 5-integrin and for the vWF antigen, are shown in Fig. 6A
. Although most of the blood vessels present in 5-null tumors are host derived because they stain positively for the presence of 5-integrin, some vessels (<5%) are ES cell derived; the endothelial cells are, in fact, negative for 5-integrin (Fig. 6A)
. From the anti-vWF or PECAM stainings performed, it was possible to analyze the area occupied by vessels. Vessel areas were quantitated in randomly selected fields in sections from 5-null or WT cell-derived tumors as described in "Materials and Methods." Twenty fields of control teratocarcinomas and 16 fields of 5-null tumors were counted (Table 1)
. The values were expressed in pixels, and each value represents the mean area of all of the vessels present in one field (x40). The average vessel area in WT was 10916 pixels, and the average vessel area in 5-null was 1424 pixels.
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A (Fig. 6B)
. In both types of teratocarcinomas, staining for SMA was found around the vessels (costaining for PECAM or vWF), indicating that recruitment of pericytes and/or smooth muscle cells was occurring.
The unique ligand for 5-integrin is FN. It is known that the deposition of FN-splicing variants around vessels is increased during angiogenesis (41, 42, 43, 44)
. To analyze whether the deposition of FN-specific splicing variants in teratocarcinomas was affected by the absence of 5-integrin, we stained the teratocarcinomas for EIIIA-FN or EIIIB-FN. Endothelial cells were identified by PECAM expression. The stainings for EIIIB were similar in 5-null tumors and controls. Although EIIIA-positive staining was observed in all tumors analyzed, a slight decrease of expression was noted around the vessels in 5-null tumors (Fig. 6, C and D)
.
5-Null ES Cells Can Differentiate into Endothelial Cells in Vitro; However, Vessel Formation Is Delayed.
To study the differentiation of ES cells into endothelial cells in vitro, 5-/-, 5+/-, or WT ES cells were grown in suspension for 6 days to form EBs (36)
. The bodies were plated on gelatin-coated coverslips and induced to differentiate. Growth factors promoting vessel formation (vascular endothelial growth factor, basic fibroblast growth factor, erythropoietin, and interleukin 6) were added to the medium to stimulate endothelial and blood cell differentiation and vessel formation. The EBs were analyzed after 5 or 7 or 11 days of adhesion and differentiation. Fig. 7
shows that at days 5 and 7 of differentiation, the 5-null EBs have a delay in attachment and in growth, whereas by day 11, the 5-null EBs look similar to the controls. The presence of endothelial cells and vessel formation were analyzed by staining the bodies for PECAM or vWF. Endothelial cells are already present at day 5 of differentiation in all EBs; however, the organization into tubular structures (vessels) is delayed in 5-null EBs. At day 7, vessels are already present in control EBs; however, it is only at day 11 that endothelial cells organize into tubular structures in 5-/- EBs (Fig. 7B)
. The differentiation of blood cells was also delayed in 5-null; in Fig. 7A
, a delay in the formation of dark/brown areas corresponding to blood cells can be observed.
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5-integrin does not greatly affect FN synthesis, deposition, or organization (data not shown). |
DISCUSSION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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5ß1-integrin enhances tumorigenesis (12
, 13
, 16
, 23, 24, 25, 26)
, we observed that 5-null teratocarcinomas grow more slowly (Figs. 1
and 2
). This result is more in line with results on ß1-null teratocarcinomas (30)
, although 5-null teratocarcinomas develop more rapidly than do ß1-nulls. Furthermore, our data allow a more precise assignment of defects to a single integrin, 5ß1. It is notable that 5-null cells can give rise to a wide variety of cell and tissue types (Fig. 3)
, consistent with earlier data on chimeric mice (34)
. Embryos completely lacking 5 integrin fail to progress beyond the 10–12 somite stage (15
, 45)
. The most likely cause of abortive development of 5-null embryos and reduced growth of 5-null teratocarcinomas is defects in vascular development in the absence of 5ß1. 5-null embryos exhibit defects in vessel formation, and we report here that 5-null teratocarcinomas are poorly vascularized (Table 1)
and that 5-null EBs show delayed and reduced formation of tubular endothelial structures (Fig. 7)
. Many of the blood vessels within the 5-null teratocarcinomas are host derived (Figs. 3H
and 6A
). This invasion by host vessels presumably supports the differentiation observed, which is much greater than is seen in 5-null embryos.
All of the data taken together demonstrate that 5-null endothelial cells can differentiate in embryos (15
, 45)
, teratocarcinomas (Fig. 6A)
, and EBs (Fig. 7)
. However, in all of these cases, they show defects in their ability to assemble into a vascular network. Similar (indeed more severe) defects are observed in FN-null embryos (15
, 35
, 46)
. Consistent with these genetic data, it has been shown recently that inhibitors of 5ß1 and FN interactions interfere with vasculogenesis and angiogenesis (47)
. Clearly, binding of FN to 5ß1 plays important roles in blood vessel development. Even the 5-positive host-derived vessels are smaller than in controls. This could be attributable to the presence of 5-null endothelial cells derived from the tumors or to defects in other cell types (pericytes, smooth muscle, or stromal cells). It was seen previously that when CHO cells defective in 5ß1-integrin were injected into nude mice, the vasculature of these tumors was abnormal, although clearly host derived (48)
, suggesting that the level of 5ß1 in the tumor parenchymal cells can influence the formation of the host vasculature invading the tumor. This somewhat surprising result could be a consequence of failure of 5-null cells to organize an appropriate FN-rich matrix to support angiogenesis or could reflect compromised function of 5-null perivascular cells, either in their ability to induce endothelial tubes or in their ability to cooperate in vessel formation.
Returning to the question of roles for 5ß1 in tumor growth per se, it is worth recalling that chimeric mice containing a significant proportion of 5-null cells do not develop increased numbers of tumors (34)
, and heterozygosity for 5 or FN does not alter the spectrum or malignancy of tumors developing in p53-deficient mouse strains (27)
. These results are consistent with the data presented here, which show reduced rather than increased tumor growth in the absence of 5ß1 (Figs. 1
and 2
). Our data suggest that both reduced proliferation and increased apoptosis of 5-null cells contribute to this slower growth. One possibility is that this is a secondary consequence of the reduced vasculature. A second possibility is that the absence of 5ß1 from some cells in itself allows or induces apoptosis. This has been demonstrated for several cell types in vitro (17
, 49, 50, 51, 52)
and for neural crest cells in vivo (45)
.
In conclusion, 5ß1/FN interactions clearly play an important part in vascular development. Indeed, they appear more important than interactions of vß3- or vß5-integrins with their ligands, because mice lacking vß3 (53)
or vß5 (54)
are viable and fertile, and mice lacking all v integrins show extensive vasculogenesis and angiogenesis (55)
, far more than mice lacking ether 5ß1 or FN. In contrast with this primary role in vascular development, 5ß1 and FN play less of a role in tumor development. Loss of 5ß1/FN interactions in tumors do not appear to be sufficient to lead to excessive tumor growth. The reduced growth of 5-null tumors may reflect decreased proliferation or increased apoptosis of tumor cells lacking 5ß1 as well as reduced vascularity. Loss of 5ß1/FN interactions may still contribute to tumor progression when other alterations in oncogenes and/or tumor suppressor genes subvert controls on proliferation and survival.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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1 This work was supported by the Howard Hughes Medical Institute (HHMI) and by Program of Excellence Grant PO1 HL41484 from the National Heart, Lung, and Blood Institute. R. O. H. is a HHMI investigator, and D. T. is a HHMI associate. 
2 To whom requests for reprints should be addressed, at Howard Hughes Medical Institute and Center for Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139. Fax: (617) 253-8357; E-mail: ROHynes{at}mit.edu
3 The abbreviations used are: ECM, extracellular matrix; FN, fibronectin; EB, embryoid body; ES, embryonic stem; LM, laminin; PECAM, platelet endothelial cell adhesion molecule; SMA, smooth muscle -actin; TN-C, tenascin; vWF, von Willebrand factor; WT, wild type; TUNEL, terminal transferase biotinylated-dUTP nick-end labeling.
4 S. E. Francis and R. O. Hynes, unpublished data.
Received 1/12/01. Accepted 5/ 2/01.
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REFERENCES |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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5ß1 fibronectin receptor suppress the transformed phenotype of Chinese hamster ovary cells. Cell, 60: 849-859, 1990.[Medline]
5 integrin-deficient mice. Development (Camb.), 119: 1093-1105, 1993.[Abstract]
5ß1 expression negatively regulates cell growth: reversal by attachment to fibronectin. Mol. Biol. Cell, 6: 725-740, 1995.[Abstract]
5ß1 integrin supports survival of cells on fibronectin and up-regulates Bcl-2 expression. Proc. Natl. Acad. Sci. USA, 92: 6161-6165, 1995.5ß1 integrin-mediated cell spreading on fibronectin. J. Biol. Chem., 268: 21459-21462, 1993.2, -3, -5 and -6-integrin receptors in pancreatic carcinoma. Int. J. Cancer, 52: 827-833, 1992.[Medline]
5 integrin/fibronectin interactions in tumorigenesis. Cancer Res., 58: 848-853, 1998.5 integrin. J. Cell Biol., 143: 849-859, 1998.4 integrin functions in the development of mouse skeletal muscle. J. Cell Biol., 135: 829-835, 1996.5 integrin-null embryos. Development (Camb.), 124: 4309-4319, 1997.[Abstract]
5ß1 with the central cell-binding domain of fibronectin. Am. J. Pathol., 156: 1345-1362, 2000.5 subunit in HT29 colon carcinoma cells suppresses apoptosis triggered by serum deprivation. Exp. Cell Res., 224: 208-213, 1996.[Medline]
5ß1 integrin protects intestinal epithelial cells from apoptosis through a phosphatidylinositol 3-kinase and protein kinase B-dependent pathway. Mol. Biol. Cell, 11: 1973-1987, 2000.5ß1 suppresses apoptosis triggered by serum starvation but not phorbol ester in MCF-7 breast cancer cells that overexpress protein kinase C-. Int. J. Oncol., 18: 195-201, 2001.[Medline]
v integrins. Cell, 95: 507-519, 1998.[Medline]This article has been cited by other articles:
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|
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|
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|
 |
|
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|
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|
 |
|
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|
|
|
|
 |
|
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|
|
|
|
 |
|
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|
|
|
|
|
|
D. Taverna, H. Moher, D. Crowley, L. Borsig, A. Varki, and R. O. Hynes Increased primary tumor growth in mice null for {beta}3- or {beta}3/{beta}5-integrins or selectins PNAS, January 20, 2004; 101(3): 763 - 768. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
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|
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|
|
 |
|
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|
|
|
|
|
|
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|
|
|
|
|
|
S. E. Francis, K. L. Goh, K. Hodivala-Dilke, B. L. Bader, M. Stark, D. Davidson, and R. O. Hynes Central Roles of {alpha}5{beta}1 Integrin and Fibronectin in Vascular Development in Mouse Embryos and Embryoid Bodies Arterioscler Thromb Vasc Biol, June 1, 2002; 22(6): 927 - 933. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R.O. HYNES, J.C. LIVELY, J.H. MCCARTY, D. TAVERNA, S.E. FRANCIS, K. HODIVALA-DILKE, and Q. XIAO The Diverse Roles of Integrins and Their Ligands in Angiogenesis Cold Spring Harb Symp Quant Biol, January 1, 2002; 67(0): 143 - 154. [Abstract] [PDF]
|
|
|
|
|
|
B. P. Eliceiri Integrin and Growth Factor Receptor Crosstalk Circ. Res., December 7, 2001; 89(12): 1104 - 1110. [Abstract] [Full Text] [PDF]
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