Genotoxic stress-mediated cell cycle activities for the decision of cellular fate.

Genomic integrity maintenance is critical for prevention of a wide variety of adverse cellular effects including apoptosis, cellular senescence, and malignant cell transformation. Coupled with normal replication, the local intracellular and extracellular stresses cause damage to cellular DNA that is recognized and repaired by the DNA damage response (DDR) pathway. p53 induces the transcription of genes that negatively regulate progression of the cell cycle in response to DNA damage, and thus participates in maintaining genome stability. p53 and many other anti-proliferative factors such as TGF beta regulate the expression of different cyclin-dependent kinase inhibitors (CDKIs). Paradoxically, one of the cellular proliferative factors, c-Myc proto-oncogene also controls the expression of these CDKIs and modulates the fate of cell in response to DNA damage. Furthermore, involvement of numerous other proteins in the DDR and crosstalk between them are likely to substantiate the DDR as one of the genome's most extensive signaling networks. Versatile protein kinases in this network affect the decision about four basic cellular fates, which are quiescence, apoptosis, oncogenesis and senescence, in response to DNA damage.