In the case of cytosolic HSP70, its signaling functions seems to be mediated mainly by interaction with its co-chaperone BAG-3 (see [151] for review), but in the case of other HSP70s, it is not fully clear how such functions are realized in cancer cells and CSCs, although a number of cancer-related signaling axes that involve HSP70s have been described. This evidence concerns the gene BAG3 and cancer.