PHB2 and colon carcinoma: In addition, in the human colon carcinoma cell line HCT 116, PHB1 and PHB2 contribute to PIG3-mediated apoptosis by binding to the P53 inducible gene 3 (PIG3) promoter (TGYCC)15 motif and initiating the transcription of PIG3 in the absence of p53 [29].