In previous studies, partial inhibition of GRP78 expression, through antisense or RNA interference approaches, did not affect the survival of tumor cells.26, 27 However, SubA-induced cleavage of GRP78 led to cell death.12 A number of mechanisms can be considered to explain significant activity of EGF-SubA despite incomplete GRP78 downregulation. Here, HSPA5 is linked to neoplasm.