Effect of OLFM4 shRNA on ATRA-mediated AML-193 cell growth, differentiation, and apoptosis. (A) AML-193 cells were transduced with lentiviral OLFM4 shRNA or control shRNA, and puromycin-resistant cell populations were selected. Blots of cell lysates were subjected to Western blotting with OLFM4 antibody, then stripped and reprobed with β-actin antibody. (B) Puromycin-enriched AML-193 cells transduced with OLFM4 shRNA or control shRNA were treated with ATRA (1μM) or vehicle for 4 days. Cell numbers were counted with trypan blue exclusion. Data represent the mean ± SD of 3 independent experiments. *P < .05, when OLFM4 shRNA was compared with control shRNA, and when OLFM4 shRNA + ATRA was compared with control shRNA + ATRA. (C) Puromycin-resistant AML-193 cells transduced with OLFM4 shRNA or control shRNA were treated with ATRA (1μM) or vehicle for 4 days. The expression of CD11b was analyzed by flow cytometry. A representative experiment is shown in the left panel, and the percentage of CD11b⁺ cells is presented in the right panel. Data represent the mean ± SD of 3 independent experiments. *P < .05. (D) Puromycin-resistant AML-193 cells transduced with OLFM4 shRNA or control shRNA were treated with ATRA (1μM) or vehicle for 4 days. Cell apoptosis was analyzed with annexin V–propidium iodide staining using flow cytometry. A representative analysis is shown in the left panel, and the percentage of apoptotic cells is shown in the right panel. Data represent the mean ± SD of 3 independent experiments. *P < .05.