HSPA5 and breast cancer: The HSP resident in the ER called HSPA5 (GRP78 or BiP) was observed in cell culture medium and cell membrane after ER stress in human rabdomiosarcoma cells (TE671) and breast cancer cells (MCF7) [141,142] and the ability to secrete HSPA5 has been linked to resistance to the antiangiogenic agent Bortezomib.