Quantified via Western blotting using an antibody against VDACs (Cell Signaling Technologies, Beverly, MA). To evaluate ATP production, cells were collected either 48 or 72 h post-transfection, and ATP assays were performed using an ATP Assay Kit (EMD Biosciences, Bedford, MA). To measure the effect of VDACs during osteoclast formation, siRNA-transfected cells were replated at 1.5 103 cells per we