To point out the effect of the dual treatment encompassing the inhibition of xCT activity and the reactivation of mut-p53, we employed different breast carcinoma cell lines harboring different p53 mutational states and expressing xCT, as determined by cytofluorimetric analyses (Supplementary Figure S1): 4T1 (triple negative; p53 null) [27] and TS/A (Her2+; p53R270H) [28] mouse mammary cancer cell lines; MCF-7 (ER+; p53 wild-type) and MDA-MB-231 (triple negative; p53R280K) human breast cancer cell lines [29]. The gene discussed is ERBB2; the disease is breast carcinoma.