Expression inhibition of CDK6 and TAB2 increases ATRA-induced differentiation in NB4 cells and PMA-induced differentiation in THP-1 cells. (A) THP-1 cells treated with 50 ng/mL PMA (left) and NB4 cells treated with 2μM ATRA (right) were collected at the indicated time points for Western blot analysis of TAB2 and CDK6 protein levels. GAPDH was used as a loading control. (B) THP-1 and NB4 cells were transiently transfected with control siRNA (si_control), TAB2 siRNA (si_TAB2), or CDK6 siRNA (si_CDK6). A representative Western blot detecting TAB2 and CDK6 is shown. (C) Real-time PCR analysis of the CD11b mRNA level in the transfected NB4 cells after ATRA induction, and real-time PCR analysis of the CD14 mRNA level in the transfected THP-1 cells after PMA induction. Error bars represent mean ± SD (n = 3). (D) Flow cytometric analysis of CD11b levels. The cells were transfected with the indicated inhibitors and then treated for 72 hours with ATRA (for NB4 cells) or PMA (for THP-1 cells). A representative experiment of 3 is presented. (E) Statistical analysis of the flow cytometric assays. Data are mean ± SD from 3 independent experiments. *P < .05 (Student t test). **P < .01 (Student t test).