HSPA5 and cancer: Additionally, a novel cyclic peptide, BC71, present in the AMOP structural domain of ISM1 was shown to be a pro-apoptotic ligand for GRP78 on the cell surface, and their combination could activate apoptotic signals like p53 and caspase-8 in human umbilical vein endothelial cells to cause apoptosis in cancer cells (Kao et al. 2018).