Norcantharidin (NCTD) exerts anti-tumor effects such as growth suppression, mitochondrial depolarization, and apoptosis induction in renal cancer cells through ER stress; this is accompanied by an increase in the expression of GRP78, p-elF2α, ATF4, and the CHOP protein in vivo and in vitro [52]. The gene discussed is ATF4; the disease is renal carcinoma.