Targets of oncogenes and tumor suppressors: Key for understanding basic mechanisms of carcinogenesis

Changes in expression of protooncogenes and tumor suppressor genes play a k ey role in oncogenesis. Dysfunction of their protein products leads to abno rmal regulation of signaling pathways, which control the cell cycle, apopto sis, genetic stability, cell differentiation, and morphogenetic reactions. Changes in these important physiological processes are obviously responsibl e both for initial steps of neoplastic cell transformation and for determin ation of subsequent tumor progression resulting in the development of malig nant tumors.