HSPA5 and cancer: The difference is reflected by the facts that first, versipelostain mainly causes apoptosis to glucose deprived cancer cells [14], [15], while pyrvinium also triggers necrosis [16] with significantly higher potency (IC50: 0.03–0.1 μM vs. 1–3 μM) in cytotoxicity and inhibition of GRP78 (10∼100 fold); second, there absolutely is no structural similarity between the two (Figure S3); third, while UPR has been demonstrated to be causally linked to pyrvinium action, the similar causal role of UPR for versaipelostain action has yet been reported.