Corosolic acid was proven able to inhibit cell growth and induce apoptosis in PC-3 and DU145 human prostate cancer cell lines thus showing potential for the therapy of castration-resistant prostate cancer; it activated two pro-apoptotic signaling pathways associated with endoplasmic reticulum stress as suggested by increased levels of specific endoplasmic reticulum stress markers such as IRE-1/ASK1/JNK and PERK/eIF2α/ATF4/CHOP finally leading to AKT inactivation and cell death (199). Here, ATF4 is linked to prostate cancer.