ATR and breast carcinoma: In breast cancer cells, hypoxia induces splice-dependent intron-retention nonsense mediated decay (NMD) of TP53, ATR, BRCA2 and Bax tumour suppressor mRNAs, de-regulating the DNA damage response, TP53 involvement in cell cycle arrest and BAX-dependent apoptosis, TP53 expression and function, and represses TP53-target and related gene expression [56].