N-α-Tosyl-L-phenylalanylchloromethane is a proteinase inhibitors with apoptotic function. Studies have shown that it induces caspase-dependent apoptosis in Epstein-Barr virus (EBV)-transformed human B cell lines with release of pro-apoptotic proteins from mitochondria. It also results in down-regulation of the anti-apoptotic proteins and caspase-dependent cleavage of two anti-apoptotic proteins. It promotes dephosphorylation of p53 on serine residues.