We discovered that phosphodiesterase 5 inhibitors such as sildenafil (Viagra) and tadalafil (Cialis) synergized with OSU-03012 to kill a wide variety of tumor cells through enhanced PERK-dependent ER stress and autophagy, as well as through activation of the death receptor CD95 (FAS-R) [7]. Here, EIF2AK3 is linked to neoplasm.