HSPA5 and cancer: Correlations between UPR activation and chemotherapy resistance were mainly demonstrated in cellular models in many types of cancer (Table 5).46, 47, 48, 51, 52, 53, 54, 57, 60, 62, 64, 71, 72, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130 A vast number of these studies demonstrate the impact of GRP78 expression on drug resistance mainly involving a reduced effect of drug-induced apoptosis.47, 48, 54, 60, 64, 116, 117, 120, 123, 125, 128, 129 However, the precise molecular mechanisms involved remain to be discovered.