TP53 and breast cancer: Experiments using lung cancer (A549: WT p53) and breast cancer (MDA-MB-231: homozygous mutant p53 DBD, R280K) cell lines showed hypoxia led to induction of Δ133TP53 and 3’TP53β expression in A549 cells but not MDA-MB-231 cells (Supplementary Fig. S8).