Figure 1.

Loss of p53 function and effects on tumor heterogeneity. In normal epithelia, p53 represses expression of potential oncogenes (for example, CD44, NANOG, BIRC5, CDC25C) as well as transcriptionally activating tumor suppressor pathways [10]. Loss of p53 allows genetic instability as well as expansion or acquisition of stem cell features during carcinogenesis. These pathways combine to generate the phenotypic heterogeneity and plasticity observed in tumors.