Enhancement of RANKL responses by MafB siRNA in BMMs. (A) Control or MafB siRNAs were transfected into BMMs. Total RNA was harvested from cultured cells 48 hours after transfection, and RT-PCR was performed with the primers specific for MafB and HPRT (control). (B) BMMs transfected with control or MafB siRNA were cultured for 3 days in the presence of M-CSF and various concentrations of RANKL. Cultured cells were fixed and stained for TRAP. (C) TRAP⁺ MNCs having more than 3 nuclei were counted as osteoclasts (*P < .01 versus control Si). Data represent mean ± SD of triplicate experiments. (D) BMMs transfected with control or MafB siRNA were cultured with M-CSF and RANKL (50 ng/mL) for the indicated times. Total RNA was harvested from cultured cells and RT-PCR was performed with primers specific for MafB, NFATc1, OSCAR, TRAP, and HPRT (control).