Figure 1.

Tumor suppressor p53 and its signaling pathway. A wide variety of intracellular and extracellular stress signals are detected by the cell and communicated to the p53 protein by numerous mediators (shown are representative mediators). Stress signals result in the degradation of the MDM2 protein and the increase in the levels and activity of the p53 protein. Depending on the cell type, environmental context and the type and/or degree of stress, activated p53 selectively transcribes a group of its target genes (shown are representative genes) and initiates various cellular responses to exert its function in tumor suppression.