miR-21 rescued osteoclastogenesis in Dicer-deficient BMMs. (A) Total RNA was prepared from Dicer wt (Dicer^wt/wt;CD11b-Cre) BMMs and Dicer KO (Dicer^F/F;CD11b-Cre) BMMs. QRT-PCR was performed with primer for miR-21. The PCR products were normalized to U6 level for each reaction. The data represent the means ± SDs of 3 experiments in triplicate. (B) Immunoblotting analysis of PDCD4 in infected BMMs without RANKL treatment. (C) TRAP-positive multinucleated cells counted at 3 days after RANKL treatment, cultured in 24-well plates (200×). Similar findings were obtained in 4 independent sets of experiments. OC indicates osteoclast.