Effect of RPS15A knockdown on colony formation of U2OS cells. (A) Photomicrographs of U2OS cell monoclone (scale bar: 250 μm). (B) Photomicrographs of U2OS cell colonies in six-well plates. (C) The number of colonies in U2OS cells with three treatments [Con, Lv-shCon, and Lv-shRPS15A(S1)]. Con, no lentivirus treatment; Lv-shCon, control lentivirus; Lv-shRPS15A, lentivirus containing an shRNA targeting RPS15A. **p<0.01.