ANGIOGENESIS FACTORS AND TUMOR-GROWTH

The formation of new blood vessels (angiogenesis) is a crucial step in the development of most solid tumors. Major advances in the identific ation of molecular actors that are presumably involved in the angiogen ic process have been obtained by studies on cultured endothelial cells . However one may wonder if these actors that are active in vitro and in various angiogenic assays are actually expressed in vivo during ang iogenesis. Using specific nucleotidic probes and antibodies it became recently possible to detect in vivo these presumptive molecular actors including angiogenic factors, matrix degrading proteases and their in hibitors, and transcription factors. The results of this contextual an alysis, although fragmentary, challenge the models derived from in vit ro analysis. These results will be essential for designing specific st rategies aiming at the inhibition of tumor angiogenesis, which may res ult in limiting the proliferation and spreading of tumor cells.