Furthermore, under severe acidic conditions and hypoxia, which recapitulate the tumor microenvironment, microvascular endothelial cells increase GRP78 expression, acquire antiapoptosis capacities and resist to sunitinib, an antiangiogenic drug.140 GRP78 knockdown resensitizes endothelial cells to drug treatment.140. This evidence concerns the gene HSPA5 and neoplasm.