PHB1 and colon carcinoma: Consistently, in the HCT 116 human colon carcinoma cell line, PHB1 was exclusively expressed in the nucleus, while PHB2 appeared to be present in both the cytoplasm and the nucleus, and knockdown of PHB1 or PHB2 inhibited apoptosis induced by the topoisomerase I inhibitor camptothecin in this cell type [29].