Oncogenes, Growth Factors, and Signal Transduction

HOW external growth signals are transmitted from the surface of the cell to the nucleus is one of the fundamental problems of cell biology. Research in the field of signal transduction has been motivated by the assumption that understanding the signal pathways responsible for cell growth will yield insight into the uncontrolled growth seen in cancer. Recently, this assumption has been supported by the discovery that many oncogenes are altered versions of the normal genes that control cell growth.1 2 3 These genes, implicated in the process of oncogenesis, encode proteins that function at every level of growth regulation. On encountering a . . .