FIG. 9.

Schematic representation of p53-mediated transactivation and transrepression. (A) p53 associates with the promoters of activated genes, e.g., p21 and Perp; coactivator molecules, represented in green, are recruited, allowing transactivation. Hypoxia-induced p53 is associated with the same promoters, but the coactivator molecules are not recruited, and therefore, transactivation does not occur. (B) p53 associates with the promoters of repressed genes, such as Cdc25C and Ankyrin-like repeat protein, along with corepressor molecules, represented in red. It is unclear if this mode of action is significant during hypoxia. (C) p53 repression does not require direct association with gene promoters. It seems likely that repressive cofactors or intermediates, indicated in red, are involved in this scenario.