FOXP1 regulates SIRT1 gene expression after transcription. MV4-11 (A-C) or MOLM-14 (D-E) AML cells were transduced with the indicated shRNA- (A-E) or complementary DNA–encoding (C) lentiviral vectors and maintained in culture for 3 days; as indicated, cells were then incubated with cycloheximide for increasing time (E), or with doxycycline for 15 hours (C). (A-C,E) Protein expression was assessed via western blot; β-actin was used as a loading control; as indicated (E) (right), SIRT1 protein expression was quantified, normalized to β-actin level, and expressed relative to levels observed before cycloheximide addition; (D) FOXP1 and SIRT1 RNA levels were assessed via reverse transcription quantitative polymerase chain reaction and expressed relative to mean level of control untransduced (−) cells (n = 4). Ctl, shControl (luciferase); EV, empty vector.