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Oncogene activation and tumor suppressor gene loss are well known as events that are responsible for the dramatic cell autonomous deregulation of growth that characterizes all malignant cells. Data accumulating more recently indicate that these same genes are also responsible for the development of a second essential characteristic of all malignant cells, the ability to induce angiogenesis on which their progressive growth in vivo depends. Oncogene activation appears to make distinctly different contributions to the angiogenic phenotype of developing tumors. Cells in which an oncogene is activated become more an- giogenic usually because they increase their secretion of inducer of angiogenesis. Inducer enhancement seems to be essential if a normal cell is to develope into a tumor cell able to grow and metastasize in vivo.
Oncogene activation and tumor suppressor gene loss are well known as events that are responsible for the dramatic cell autonomous deregulation of growth that characterizes all malignant cells. Data accumulating more recently that those same genes are also responsible for the development of a second essential characteristic of all malignant cells, the ability to induce angiogenesis on which their progressive growth in vivo depends. Oncogene activation appears to make distinctly different contributions to the angiogenic phenotype of developing tumors. Cells in which an oncogene is activated become more an- giogenic normally because they increase their secretion of inducer of angiogenesis. Inducer enhancement seems to be essential if a normal cell is to develope into a tumor cell able to grow and metastasize in vivo.