Expression of pro-apoptotic Bfk isoforms reduces during malignant transformation in the human gastrointestinal tract.

Reduced expression of pro-apoptotic Bcl-2 family proteins has been described in many gastrointestinal cancers, and may play a role in tumourigenesis. The human homologue of the pro-apoptotic Bcl-2 protein, Bfk, is predominantly expressed in tissues of the gastrointestinal tract. In colon, four alternatively spliced isoforms were identified; of which two are pro-apoptotic when overexpressed.

Three novel Bid proteins generated by alternative splicing of the human Bid gene.

Bid, a BH3-only Bcl-2 protein, is activated by proteolytic cleavage exposing the BH3 domain, which then induces apoptosis by interacting with pro-apoptotic Bcl-2 family proteins (e.g. Bax and Bak) at the mitochondrial surface.