HSPA5 and cancer: Tumor-secreted GRP78 can block the antiangiogenic activity of bortezomib through inducing pro-survival signals via phosphorylation of extracellular signal–related kinase and inhibiting p53-mediated expression of pro-apoptotic Bok and Noxa proteins in endothelial cells, and it can differentiate bone marrow-derived mesenchymal stem cells (BMSCs) into cancer-associated fibroblasts (CAFs) through activating TGF-β/Smad signaling pathway in an autocrine/paracrine manner [8, 10].