Loss of RNF43 function confers resistance to DNA damage-induced cell death. (A) RNF43 mRNA levels in AGS and MKN45 gastric cancer cells upon increasing doses of γ-radiation. Cycle threshold (CT) values were normalized to GAPDH and fold change was calculated over untreated cells (N = 4). (B) Cell viability of WT AGS, AGSD196fs, control MKN45 (shCtrl), and RNF43 knockdown MKN45 (shRNF43) cells after γ-radiation. Values were normalized over untreated cells (N = 4). (C) Cell viability of AGS, AGSD196fs cells, as well as control AGS and MKN45 (shCtrl) and RNF43 knockdown AGS and MKN45 (shRNF43) cells under basal conditions (N = 3). (D) Representative images and quantification of cell colonies after γ-radiation (N = 4). (E) Flow cytometry analysis of Annexin V and propidium iodide (PI)-positive AGS and MKN45 cells after irradiation. Values were normalized over untreated cells (N = 4). Error bars indicate SD. ∗P ≤ .05, ∗∗P ≤ .01, ∗∗∗P ≤ .001, 2-tailed unpaired t test. mRNA, messenger RNA.