Anti-growth effect of AZD6738 in biliary tract cancer (BTC) cells. (A) Basal expression levels of ataxia-telangiectasia and Rad3-related (ATR), ataxia-telangiectasia mutated (ATM), and p53 in nine BTC cell lines analyzed by western blotting. The intensity was quantified using imageJ software. The intensity greater than “1” was classified as high expression, less than “0.6” was classified as low expression. (B) Anti-proliferative effects of AZD6738 in nine BTC cell lines evaluated by MTT assays (left) and colony-forming assays (CFA) (right). (C) Western blot analyses evaluating the effect of AZD6738 on signaling pathways in four BTC cell lines. SNU478, SNU869, SNU245, and SNU2670 cells were treated with increasing concentrations of AZD6738 (0, 0.1, 0.5, and 1 μM) for 5 days, after which protein extracts were immunoblotted with the indicated antibodies.