To investigate the role of the three commonly recognized direct activator BH3-only proteins, Bim, Bid (tBid), and Puma, in Bax/Bak activation, a combination of transcription activator-like effector nucleases (TALEN)35 and CRISPR-Cas936, 37 techniques was used to generate human colon cancer HCT116 cells deficient for all three proteins. Here, BAK1 is linked to malignant colon neoplasm.