BAK1 and squamous cell carcinoma: On this basis, BH3 domain hydrophobic peptides of the Bax, Bad, and Bak proteins once coupled to the Antennapedia fusogenic peptide (cell-permeable Bax BH3 peptides) to make them permeable to squamous cell carcinoma tumor cells and T-cell acute leukemia cells, blocking the activity of Bcl-XL and Bcl-2 and restoring apoptosis [28].