In this study, we found that expression of Klf4 was significantly lower in AML patients than in normal controls, consistent with previous findings.29 Furthermore, we identified that forced expression of Klf4 significantly inhibited cell proliferation by inducing cell cycle arrest and increasing the expression of p21 and p27 in vitro and in vivo. The gene discussed is CDKN1A; the disease is acute myeloid leukemia.