CASP2 and esophageal cancer: To examine if caspase-2 plays a role in ferroptosis, we used small interfering RNA (siRNA) to knockdown caspase-2 in isogenic parental p53null and mut-p53 overexpressing (p53R273H) lung cancer cells (H1299) and a mut-p53 esophageal cancer cell line (Flo-1) (Fig. 1a).