
[Cancer Research 60, 896-900, February 15, 2000]
© 2000 American Association for Cancer Research
p53 Phosphorylation and Association with Murine Double Minute 2, c-Jun NH2-Terminal Kinase, p14ARF, and p300/CBP during the Cell Cycle and after Exposure to Ultraviolet Irradiation1
Thomas Buschmann,
Victor Adler,
Ekaterina Matusevich,
Serge Y. Fuchs and
Zeev Ronai2
Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, New York 10029
 |
ABSTRACT
|
|---|
p53 phosphorylation and association with proteins is implicated in its
stability and activity. We have compared the association of DNA-bound
and overall pools of p53 with murine double minute 2 (Mdm2), c-Jun
NH2-terminal kinase (JNK), p300/CBP, and p14ARF
during cell cycle progression. Whereas DNA-bound p53 associates with
JNK at G0-G1 and with Mdm2 and p300 during S
and G2-M phases, the general pool of p53 was found in
complex with JNK and Mdm2 almost throughout the cell cycle.
Phosphorylation of p53 at serines 9, 15, and 20 is at the highest
levels at G1 and at serines 37 and 392 during
G2-M phase. Whereas a high dose of UV irradiation was
required for phosphorylation of serines 15 and 392 between 8 and
24 h after treatment, a low dose caused immediate phosphorylation
on serines 9, 20, and 372. These dynamic changes in the phosphorylation
of p53 are expected to play a pivotal role in p53 association,
stability, and function.
 |
Introduction
|
|---|
The p53 tumor suppressor gene encodes a
short-lived transcription factor (1
, 2)
, which is
stabilized in response to a variety of stresses (3)
.
Posttranslational modifications of p53 by phosphorylation and
acetylation have been implicated in its stability and transcriptional
activation (3)
. Among cellular proteins that have been
shown to play a direct role in regulating p53 stability and
transcriptional activity are
Mdm23
(4
, 5)
, JNK (6
, 7)
,
p14ARF (8)
, and p300/CBP
(9)
. The ability of Mdm2 and JNK to target degradation of
p53 is impaired as a result of phosphorylation of p53 by stress
kinases, as shown for mitogen-activated protein kinase kinase 1
(6)
, p38 (10)
, and ataxia telangiectasia
mutant/DNA-protein kinase (11
, 12)
. Whereas ataxia
telangiectasia mutant and DNA-protein kinase target p53 phosphorylation
at NH2-terminal residue 15 (12)
, p38
phosphorylates p53 at the COOH-terminal residue 389 (10)
,
and JNK was reported to phosphorylate p53 at amino acid 34
(13)
. Other kinases implicated in p53 phosphorylation
include casein kinase II, which was shown to phosphorylate amino acid
386, (14)
protein kinase C, which phosphorylates p53 on
residue 371 (15)
, and cyclin-dependent kinase 2, which
phosphorylates amino acid 315 (16)
. In addition,
acetylation on residues 320 and 373 was observed in response to DNA
damage and has been associated with p53 transcriptional activities
(17)
. Although ample reports point to p53 phosphorylation
on multiple residues, the requirement(s) and regulation of such
phosphorylation is not well understood. Upon activation, p53 induces
either growth arrest or apoptosis (18)
. Although the
mechanisms underlying the ability of p53 to elicit such opposing
effects are yet to be identified, independent studies point to a
different set of p53 regulators and effectors that are affected by p53
in each of these scenarios.
In studying the regulation of p53 stability, we demonstrated previously
that, in Swiss 3T3 cells, JNK and Mdm2 target p53 degradation in
different phases of the cell cycle (7)
. In this study, we
have compared the association of subpopulations of p53 with proteins
implicated in stability and activity of p53 and monitored the pattern
of phosphorylation during cell cycle progression and after exposure to
UV-C irradiation.
 |
Materials and Methods
|
|---|
Cells and UV Treatment.
NHFs (TIG) were kindly provided by Hidetoshi Tahara (NIEHS, Durham,
NC) and maintained in DMEM supplemented with 10% fetal bovine
serum and antibiotics. Normal human fibroblasts (70% confluent,
passages 2227) were treated with either 9 J/m2
or 50 J/m2 UV-C light (254 nm) and harvested at
indicated time points.
Cell Lysis, Immunoprecipitation, and Western Blot.
Cells were lysed in lysis buffer [20 mM HEPES (pH 7.5),
350 mM NaCl, 25% glycerol, 0.25% NP40, 1 mM
sodium vanadate, 0.5 mM phenylmethylsulfonyl fluoride, and
1 µg/ml each of aprotinin, pepstatin, and leupeptin]. Lysates were
clarified by centrifugation for 15 min at 14,000 x g at 4°C. The protein concentration was determined, and
aliquots were stored at -80°C. For immunoprecipitations, 1 mg of
extract at each time point was precleared with 10 µl of protein A/G
beads for 1 h at 4°C to remove unspecific binding. Precleared
extracts were incubated with either pAb421 or DO1 antibodies overnight
at 4°C. Protein A/G beads were added for 3 h at 4°C, and the
mixture was then centrifuged at 14,000 rpm for 10 min at 4°C. Protein
A/G beads were washed four times with PBS, 3x sample buffer was added,
and samples were boiled for 5 min. Eluted material was loaded on an 8%
SDS-PAGE and electroblotted, and Western blotting was carried out with
the indicated antibodies. For straight Western blot analysis, 150 µg
of extracts were loaded on a 8% SDS-PAGE and analyzed as described
above.
Western Blot Procedure for Phospho-Antibodies.
Cell pellet was lysed with three packed volumes of phospho-extraction
buffer [20 mM Tris-HCl (pH 7.5), 20 mM
p-nitrophenylphosphate, 1 mM EGTA, 50
mM sodium fluoride, 50 µM
sodium orthovanadate, 5 mM benzamidine, 100
mM NaCl, 5 mM
MgCl2, supplemented with 40 µg/ml DNase I, and
1 µg/ml protease inhibitors] and incubated for 10 min at room
temperature. After incubation with sample buffer for 5 min at 95°C,
samples (200 µg) were loaded and separated on a 10% SDS-PAGE and
electroblotted for 3 h at 100 V. Membrane was incubated with
respective acetylation or phospho-antibodies overnight and developed
using ECL detection.
EMSA.
For gel-shift assays, p53 prepared from NHFs (2 µg) was
immunoprecipitated with either DO1 or pAb421 antibodies. Elution of p53
from the respective antibodies was carried out by adding 75 µg of
peptides corresponding to the binding site of either DO1
(PPLSQETFSDLWKL) or pAb421 (HLKSKKGQSTSRHK) antibodies on p53. After
elution, p53 was concentrated on Mr
30,000 cutoff columns and used for EMSA. A fraction of the
eluted and dialyzed p53 was separated on 8% SDS-PAGE, followed by
immunoblot analysis to verify that equal amounts of protein are used
for gel shift reactions. An equal amount of eluted p53 (20 µl) was
mixed with DNA-binding reaction buffer [5x EMSA buffer, 40
mM spermidine, 10 mM DTT,
and 500 µg/ml poly(deoxyinosinic-deoxycytidylic acid)] and the
32P-labeled double-stranded oligonucleotide (10
ng/µl 32P probe), which harbors p53 target
sequence derived from the human p21/CIP/WAF1 promoter (sense, 5'-AAT
TCT CGA GGA ACA TGT CCC AAC ATG TTG CTC GAG-3'; antisense, 5'-CTC GAG
CAA CAT GTT GGG ACA TGT TCC TCG AGA ATT-3'). The mixture was incubated
for 30 min at room temperature. For competition experiments, excess of
unlabeled cold oligonucleotide was added to the reaction. Samples were
separated on 4% PAGE, followed by autoradiography.
 |
Results and Discussion
|
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Association of p53 with proteins that alter its stability was
carried out in NHFs using pAb421 antibodies, which recognize a
DNA-bound form of p53 (19)
, and DO1 antibodies, which
recognize p53 independent of conformation, and is expected to recognize
an overall pool of p53 molecules. Indeed, immunoprecipitations of p53
from NHF cells with each of these antibodies, followed by elution of
p53 and analysis of DNA-binding activity, revealed that
pAb421-immunoprecipitated forms of p53 exhibit a markedly higher level
of DNA-binding activity, when compared with the activity detected in
DO1 precipitates (Fig. 1)
. These findings confirm that pAb421 antibodies recognize a form of
p53, which has a greater ability of associating with p53 target
sequence. These findings also reveal that the pool of p53 molecules
recognized by the DO1 antibodies is different from those detected by
pAb421, indicating that these antibodies recognize different
subpopulations of p53 molecules.

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Fig. 1. DNA-binding activity of p53 purified by pAb421
versus DO1. Proteins from NHFs were subjected to
immunoprecipitation using pAb421 or DO1 antibodies, followed by
elution, dialysis, and analysis on Western blots for amounts of p53
(right panel). Equal amounts of p53 were taken for gel
shift reactions using 32P-labeled oligonucleotide bearing
p53 target sequence under conditions indicated in the figure.
oligo, oligonucleotide; IP,
immunoprecipitation.
|
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p53 association with proteins implicated in its stability varied
dramatically when pAb421- and DO1-recognized populations of p53 were
compared. pAb421-recognized p53 is predominantly associated with Mdm2
in the S and G2-M phases of the cell cycle,
whereas the DO1-recognized p53 was found in complex with Mdm2
throughout the cell cycle with maximal levels during
G1 and S phases (Fig. 2, II).
Analysis of JNK association with pAb421-recognized p53
identified such a complex during G0 and
G1 phases (Fig. 2, III),
as was
observed previously in mouse fibroblasts 3T3 cells (7)
.
Although higher, relative levels of JNK bound to the DO1-recognized
form of p53 decreased as the cell cycle progressed (Fig. 2, III).

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Fig. 2. Association of wild-type p53 with Mdm2, JNK, p300, and
p14ARF in different phases of the cell cycle. NHFs at a
confluence of 50% were synchronized by maintaining them in medium
containing 0.2% calf serum. Upon addition of 10% serum (time 0),
cells were harvested at the four phases of the cell cycle based on
fluorescence-activated cell sorter analysis to identify the optimal
time to represent G0 (0 h) G1 (15 h), S (21 h),
and G2-M (27 h). Cells were lysed and incubated for
immunoprecipitation (IP) with either pAb421 or DO1
antibodies overnight at 4°C. Western blots were carried out with the
indicated antibodies. The same analysis was performed using direct
Western blot analysis, in which 150 µg of extracts were loaded on an
8% SDS-PAGE and analyzed as described above.
|
|
Analysis of p300 and p14ARF association with the
pAb421-recognizable form of p53 revealed that the amounts of p300 and
p14ARF increase continuously as the cell cycle
progresses, reaching their highest levels in the
G2-M phase (Fig. 2, IV + V).
The association of p300 with p53 was limited to the pAb421-recognizable
form during the late phases of the cell cycle (Fig. 2, IV).
The association between both pAb421- and DO1-recognized forms of p53
and p14ARF was seen primarily in the
G2-M phase of the cell cycle (Fig. 2, V).
These observations suggest that association with each of the proteins
that affect p53 stability may require a different conformation of the
p53 protein, which is therefore expected to undergo dynamic changes
throughout the cell cycle.
The nature of p53 phosphorylation and acetylation was studied using p53
that has been immunoprecipitated with pAb421 antibodies, followed by
analysis with antibodies that were raised against specific
phosphoacceptor sites. Antibodies that recognize either of the
acetylation sites on amino acids 320 and 373 detected the highest
levels of acetylation in the G0 phase, which
declined as the cell cycle progressed (Fig. 3A).
Serines 9, 15, 20, and 372 are phosphorylated in the
G1 phase of the cell cycle (Fig. 3, B, C, D, and F).
Phosphorylation on Ser-37 was somewhat
higher in cells grown in the S and G2-M phases of
the cell cycle (Fig. 3E)
, whereas phosphorylation on Ser-392
was found to occur primarily during the G2-M
phase of the cell cycle (Fig. 3G)
. The active interplay
between different sites that are phosphorylated as the cell cycle
progresses suggests dynamic changes in the conformation of p53, which
in turn, alter affinity for cellular proteins, as demonstrated in Fig. 2
. That JNK is immunoprecipitated with pAb421, which also
immunoprecipitates the acetylated form of p53, implies that acetylation
and JNK association share G0-related conformation
that is recognized by pAb421. The finding that
p14ARF association with pAb421-recognized p53 at
G0 and G2-M coincides with
JNK and Mdm2 association points to possible interplay between the
stabilizing and degrading molecules. That substantial lower amounts of
JNK and no Mdm2 were found in complex with pAb421-bound p53 during
G1 phase, when most phosphorylation events were
recorded, further support the notion that phosphorylation protects
transcriptionally active p53 from degradation, as was shown previously
(6
, 7
, 11) . Finally, the association of Mdm2 and p300 with
active p53 during S-G2-M phases is in line with
recent studies, suggesting that such association is interdependent
(9)
. Together, these data suggest that p53 may elicit an
active transcriptional signal at G1 and
G2-M phases of the cell cycle.

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Fig. 3. Acetylation and phosphorylation of p53 at different phases
of the cell cycle in NHFs. At time points reflecting G0,
G1, S, and G2-M, proteins were prepared from
cells, and p53 was immunoprecipitated with pAb421 antibodies. Western
blot analysis using acetylation- or phospho-antibodies was carried out
(New England Biolabs), and proteins were detected by ECL reaction.
A, acetylation levels; B, Ser-9;
C, Ser-15; D, Ser-20; E,
Ser-37; F, Ser-372; G, Ser-392.
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Using phosphospecific antibodies, we elucidated changes in p53
phosphorylation at different time points after the administration of
low (9 J/m2) or high (50
J/m2) doses of UV irradiation. Lower doses are
implicated in p53-elicited growth arrest, whereas high doses reflect
p53-mediated apoptosis. Fig. 4II
depicts the characteristic time-dependent increase in p53
level after UV treatment. Increased phosphorylation on Ser-9 was seen
within 1 h after exposure to a high dose of UV irradiation, which
has been maintained after 4 and 8 h; after 24 h, the level of
Ser-9 phosphorylation decreased (Fig. 4A)
. Exposure to
low-dose irradiation led to a weaker yet sustained increase in Ser-9
phosphorylation, even after 24 h. The degree of Ser-9
phosphorylation 1 h after exposure to high-dose UV light was
comparable with that seen 24 h after exposure to the low dose
(Fig. 4A)
. An increase in Ser-15 phosphorylation was found
only after exposure to high-dose irradiation and not earlier than
8 h after treatment (Fig. 4B)
. Phosphorylation of
Ser-20 and Ser-37 was induced by both low- and high-dose UV, although
the high dose caused a faster and stronger increase in phosphorylation
at this site. Whereas the dose of 50 J/m2 UV
light caused the highest level of phosphorylation on Ser-37 after
4 h, exposure to the lower dose led to maximal phosphorylation
after 8 h (Fig. 4, C and D).
Both doses of
UV elicited maximal phosphorylation on Ser-20 after 4 h (Fig. 4C)
.

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Fig. 4. Acetylation and phosphorylation of p53 after low- or
high-dose UV treatment. NHFs (70% confluent) were treated with 9
J/m2 or 50 J/m2 UV-C light and harvested at the
indicated time points. Cells were lysed and processed as described in
"Materials and Methods." I, specific immunostaining
with different phospho-antibodies directed against the various serine
residues. Wild-type p53, shown in II, was detected using
monoclonal DO1 antibodies (Oncogene).
|
|
The degree of Ser-372 phosphorylation was greater and occurred faster
after exposure to high-dose irradiation, although the lower dose also
caused a noticeable increase at this phophoacceptor site (Fig. 4E)
. Conversely, Ser-392 was weakly phosphorylated 24 h
after high-dose irradiation (Fig. 4F)
. Analysis of p53
acetylation revealed a rapid (1 h) and short-lived increase after
exposure to a dose of 50 J/m2 UV light, whereas
the lower dose caused a short-lived increase after 4 h (Fig. 4G)
.
The kinetics of p53 phosphorylation in response to UV irradiation
suggest that in NHFs, phosphorylation at Ser-9, -20, -37, and -372 may
contribute to p53 stability, whereas phosphorylation on Ser-15 occurs
after p53 stabilization took place. The kinetics of p53 Ser-15
phosphorylation is in agreement with Shieh et al.
(11)
. It is important to note that earlier phosphorylation
of Ser-15 was recorded in other cell systems, including cells of ataxia
telangiectasia patients and lymphoblasts (20)
, suggesting
that changes in and contribution of respective phosphoacceptor sites is
cell type dependent. In addition, given the complex changes in p53
phosphorylation demonstrated in the present study, it is likely that
other phosphoacceptor sites do exist and are crucial for mediating p53
functions. The latter is supported by the recent reports that could not
identify major changes in stability/activity of p53 that has been
mutated in most of the phosphorylation sites studied here
(21)
.
Overall, our study provides evidence for the existence of at least two
subpopulations of p53, which differ in their phosphorylation pattern as
in their conformation. Respectively, only a subpopulation of p53, which
is recognized here by the pAb421 antibodies, is found to exhibit
dynamic changes in association with proteins that contribute to p53
stability and activity and in their phosphorylation pattern. Given the
abundant support for phosphorylation-dependent changes in p53
conformation, stability, and function, our study identifies changes in
p53 association and phosphorylation with cell cycle progression or
dose-dependent stress response, thereby breaking down the complex
regulation of p53 stability and activity.
 |
ACKNOWLEDGMENTS
|
|---|
We thank Thea Tlsty and Moshe Oren for discussion, Michael Comb
of New England Biolabs for the phospho-p53 antibodies used in
this study, and Hidetoshi Tahara for NHF cells.
 |
FOOTNOTES
|
|---|
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 Support from NIH Grant CA78419 (to Z. R.) is
gratefully acknowledged. 
2 To whom requests for reprints should be
addressed, at Ruttenberg Cancer Center, Mount Sinai School of Medicine,
1425 Madison Avenue, Room 15-20, New York, NY 10029. Phone:
(212) 659-5571; Fax: (212) 849-2446; E-mail: ronaiz01{at}doc.mssm.edu 
3 The abbreviations used are: Mdm2, murine double
minute 2; JNK, c-Jun NH2-terminal kinase; NHF, normal human
fibroblast; EMSA, electrophoretic mobility shift assay. 
Received 10/18/99.
Accepted 12/30/99.
 |
REFERENCES
|
|---|
-
Reich N., Oren M., Levine A. J. Two distinct mechanisms regulate the levels of a cellular tumor antigen, p53. Mol. Cell. Biol., 3: 2143-2150, 1983.[Abstract/Free Full Text]
-
Hall P., McKee P., Menage H., Dover R., Lane D. P. High levels of p53 protein in UV-irradiated normal human skin. Oncogene, 8: 203-207, 1993.[Medline]
-
Meek D. W. Multiple phosphorylation and the integration of stress signals at p53. Cell Signal, 10: 159-166, 1998.[Medline]
-
Haupt Y., Maya R., Kazaz A., Oren M. MDM2 promotes the rapid degradation of p53. Nature (Lond.), 387: 296-299, 1997.[Medline]
-
Kubbutat M. H., Jones S. N., Vousden K. H. Regulation of p53 stability by Mdm2. Nature (Lond.), 387: 299-303, 1997.[Medline]
-
Fuchs S. Y., Adler V., Buschmann T., Yin Z., Wu X., Jones S. N., Ronai Z. JNK targets p53 ubiquitination and degradation in nonstressed cells. Genes Dev., 12: 2658-2663, 1998.[Abstract/Free Full Text]
-
Fuchs S. Y., Adler V., Pincus M. R., Ronai Z. MEKK1/JNK signaling stabilizes and activates p53. Proc. Natl. Acad. Sci. USA, 95: 10541-10546, 1998.[Abstract/Free Full Text]
-
Pomerantz J., Schreiber-Agus N., Liegeois N., Silverman A., Alland L., Chin L., Potes J., Chen K., Orlow I., Lee H., Cordon-Cardo C., DePinho R. The Ink4a tumor suppressor gene product, p19Arf, interacts with MDM2 and neutralizes MDM2s inhibition of p53. Cell, 92: 713-723, 1998.[Medline]
-
Grossman S., Perez M., Kung A., Joseph M., Mansur C., Xizo Z., Kumar S., Howley P. M., Livingston D. p300/MDM2 complexes participate in MDM2-mediated p53 degradation. Mol. Cell, 2: 405-415, 1998.[Medline]
-
Huang C., Ma W., Maxiner A., Sun Y., Dong Z. p38 kinase mediates UV-induced phosphorylation of p53 protein at serine 389. J. Biol. Chem., 274: 12229-12235, 1999.[Abstract/Free Full Text]
-
Shieh S., Ikeda M., Taya Y., Prives C. DNA damage-induced phosphorylation of p53 alleviates inhibition by MDM2. Cell, 91: 325-334, 1997.[Medline]
-
Banin S., Moyal L., Shieh S., Taya Y., Anderson C. W., Chessa L., Smorodinsky N., Prives C., Reiss Y., Shiloh Y., Ziv Y. Enhanced phosphorylation of p53 by ATM in response to DNA damage. Science (Washington DC), 281: 1674-1677, 1998.[Abstract/Free Full Text]
-
Milne D. M., Campbell L. E., Campbell D. G., Meek D. W. p53 is phosphorylated in vitro and in vivo by an ultraviolet radiation-induced protein kinase characteristic of the c-Jun kinase, JNK1. J. Biol. Chem., 270: 5511-5518, 1995.[Abstract/Free Full Text]
-
McKendrick L., Milne D., Meek D. W. Protein kinase CK2-dependent regulation of p53 function: evidence that the phosphorylation status of the serine 386 (CK2) site of p53 is constitutive and stable. Mol. Cell. Biochem., 191: 187-199, 1999.[Medline]
-
Chernov M., Ramana C., Adler V., Stark G. Stabilization and activation of p53 are regulated independently by different phosphorylation event. Proc. Natl. Acad. Sci. USA, 95: 2284-2289, 1998.[Abstract/Free Full Text]
-
Price B., Hughes-Davis L., Parks S. Cdk2 kinase phosphorylates serine 315 of human p53 in vitro. Oncogene, 11: 73-80, 1995.[Medline]
-
Sakaguchi K., Herrera J., Saito S., Miki T., Bustin M., Vassilev A., Anderson C., Apella E. DNA damage activates p53 through a phosphorylation-acetylation cascade. Genes Dev., 12: 2831-2841, 1998.[Abstract/Free Full Text]
-
Canman C., Gilmer T., Coutts S., Kastan M. B. Growth factor modulation of p53-mediated growth arrest versus apoptosis. Genes Dev., 9: 600-611, 1995.[Abstract/Free Full Text]
-
Halazonetis T., Davis L., Kandil A. Wild-type p53 adopts a "mutant"-like conformation when bound to DNA. EMBO J., 12: 1021-1028, 1993.[Medline]
-
Siliciano J., Canman C., Taya Y., Sakaguchi K., Apella E., Kastan M. B. DNA damage induces phosphorylation of the amino terminus of p53. Genes Dev., 11: 3471-3481, 1997.[Abstract/Free Full Text]
-
Blattner C., Tobiasch E., Litfen M., Rahmsdorf H. J., Herrlich P. DNA damage induced p53 stabilization: no indication for an involvement of p53 phosphorylation. Oncogene, 18: 1723-1732, 1999.[Medline]
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 |
 
E. J. Morris, E. Keramaris, H. J. Rideout, R. S. Slack, N. J. Dyson, L. Stefanis, and D. S. Park
Cyclin-Dependent Kinases and P53 Pathways Are Activated Independently and Mediate Bax Activation in Neurons after DNA Damage
J. Neurosci.,
July 15, 2001;
21(14):
5017 - 5026.
[Abstract]
[Full Text]
[PDF]
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T. Buschmann, O. Potapova, A. Bar-Shira, V. N. Ivanov, S. Y. Fuchs, S. Henderson, V. A. Fried, T. Minamoto, D. Alarcon-Vargas, M. R. Pincus, et al.
Jun NH2-Terminal Kinase Phosphorylation of p53 on Thr-81 Is Important for p53 Stabilization and Transcriptional Activities in Response to Stress
Mol. Cell. Biol.,
April 15, 2001;
21(8):
2743 - 2754.
[Abstract]
[Full Text]
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E. Kobet, X. Zeng, Y. Zhu, D. Keller, and H. Lu
MDM2 inhibits p300-mediated p53 acetylation and activation by forming a ternary complex with the two proteins
PNAS,
November 7, 2000;
97(23):
12547 - 12552.
[Abstract]
[Full Text]
[PDF]
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