Figure 1. Regulation of ferroptosis by p53 is highly context specific. (A) The indicated cell lines were categorized based on the relative amount of cell death observed in response to 24 hours treatment with erastin in a 6-well format. After 24 hours of treatment, the sensitive cell lines had an EC50 of less than 2 μM of erastin, while the moderately sensitive cell lines had an EC50 that was greater than 2 μM, but lesser than 10 μM of erastin. In the resistant cell lines, erastin did not achieve 50% killing at this time point. (B, C) Viability of isogenic cell lines with wild-type (WT) p53 or no p53 (KO) in (B) HCT-116 and (C) RKO when treated with indicated doses of either doxorubicin (left panel) or IKE (right panel) for 24 hours. (D) Immunoblot showing p53 and p21 protein levels in HCT-116 and RKO cells. Multiple replicates of the wild-type and p53 KO cell lines cultured in separate dishes were used. Actin was used as a loading control. The data in (B, C) represent the mean ± SE for two of four independent experiments. The viability data have been normalized to that of the DMSO control.