The presence of separate signaling compartments was further demonstrated after incubation of csGRP78 expressing cancer cells with the E. coli enzyme subtilase cytotoxin A subunit (SubA), a serine proteinase that cleaves csGRP78 between amino acids Leu416 and Leu417, releasing a 28-kDa GRP78 C-terminal fragment, that abrogates C-terminal domain signal transduction pathways but keeps the N-terminal-mediated csGRP78 signaling pathways of the cells unaffected [76]. Here, HSPA5 is linked to cancer.