TP53 (p53) forms a complex with a transcription factor POU4F1 (BRN3A). This interaction involves the POU domain of POU4F1. Binding of TP53 to POU4F1 modulates the transcriptional activity of both proteins, but the exact mechanism has not been elucidated. TP53 inhibits POU4F1-mediated induction of BCL2 transcription (Budhram-Mahadeo et al. 1999). POU4F1 inhibits TP53-mediated induction of BAX and NOXA, but enhances TP53-mediated induction of CDKN1A (p21) (Budhram-Mahadeo et al. 2002, Hudson et al. 2005).