POU5F1 and breast carcinoma: Moreover, P53 activates its inhibitor, MDM2, thereby creating a negative feedback loop.[41] The cancer metastasis process involves complex regulatory interactions among P53, microRNAs, OCT4, Let7, LIN28, and BACH1.[42, 43, 44, 45, 46] Specifically, in breast cancer cells, BACH1 facilitates metastasis and suppresses the transcription of the RKIP.