CXCR4 and breast carcinoma: In breast cancer cell lines, it has been reported that the expression of CXCL12 and CXCR4 is regulated by the transcription factor POUF1 (Pit-1) and that knockdown of CXCR4 in Pit-1-overexpressing tumor cells significantly decreases tumor growth in vivo (Martinez-Ordoñez et al., 2018).