BAP31 is a 28-kDa integral membrane protein of the endoplasmic reticulumwhose cytosolicdomaincontains two caspase recognition sites that are preferentially cleaved by initiator caspases,such as caspase-8. Recently,we reported that the caspase-resistant BAP31 inhibited Fas-mediated apoptotic membrane fragmentation and the release of cytochromec from mitochondria in KB epithelial cells (Nguyen M.,Breckenridge G.,Ducret A &Shore G. (2000) Mol. –6740).