About the Cover
Cover image
The matrix metalloproteinases have been associated with invasive and metastatic properties of many tumor types. However, the exact mechanism by which they influence these processes has remained elusive. Utilizing a novel orthotopic model of neuroblastoma, the investigators have used both genetic and pharmacologic approaches to this problem. The cover figure shows vascularization of a xenotransplanted neuroblastoma tumor visual-ized by fluorescent angiography using a FITC-labeled Lycopersicon escu-lentum lectin. The top figure shows the formation of an extensive capillary network in a wild-type mouse 3 weeks after tumor implantation. The bottom figure shows the defect in the vasculature in a mouse deficient in matrix metalloproteinase-9 (MMP-9). The data demonstrate a critical role for MMP-9 in blood vessel formation and, in particular, pericyte recruit-ment to the neovasculature. For details, see the article by Chantrain et al. on p. 1675 of this issue.