Oridonin stabilizes RARα protein in leukemia cells. (A) Primary leukemia cells from three newly diagnosed AML patients were treated with 10 μM oridonin for 12 h, followed by detection of RARα protein with β-actin as a loading control. (B) Clinical data of the three AML patients. (C) NB4 cells were treated with the indicated concentrations of oridonin for 12 h (left panel) or with 10 μM oridonin for the indicated times (right panel), followed by western blot analysis of the RARα protein with β-actin as a loading control. The symbol * denotes a non-specific protein. (D) NB4 cells were treated as described in panel C, followed by the quantification of RARα mRNA by real-time RT-PCR. (E) NB4 cells were incubated with 5 μg/mL CHX alone or with 10 μM oridonin for the indicated times. Increased amounts of cell lysates compared with panel A were loaded and then blotted for the RARα protein with β-actin as a loading control. (F) NB4 cells were treated with 10 μM oridonin and/or 10 nM ATRA for 48 h, and the mRNA levels of the indicated genes were measured by real-time RT-PCR. The data are represented as fold changes against the control. The symbols * and # represent P values less than 0.05 and 0.01, respectively. All experiments were replicated three times and gave consistent results.