However, there is increasing evidence that GRP78 is also detected at other cellular sites, including the cell surface, cytoplasm, mitochondria and nucleus, and it participates in signal transduction, proliferation, invasion, apoptosis, inflammation and immunity [26] Importantly, one of the branches of GRP78 is redirected to the surface of specific types of cells, such as cancer cells, and this process is actively enhanced by endoplasmic reticulum stress to regulate different biological functions of cancer [14, 27, 28]. Here, HSPA5 is linked to cancer.