Subsequently, in human breast cancer cell lines, it was shown that inhibition of TGF-β signaling using the TGF-β type I receptor kinase inhibitor Ly 364947 decreased the clonogenic cell growth prior to irradiation, and blocked irradiation-induced γH2AX foci formation and p53 phosphorylation (18). This evidence concerns the gene TGFB1 and breast carcinoma.