Analysis of OPG expression during osteoclastic differentiation in the presence of TRAIL. At 6 and 12 days of cultures, cells were harvested and OPG expression was analyzed by RT-PCR (A) and Western blotting (B). (A) Semiquantitative OPG RT-PCR was performed on serial dilutions (1-3) of RNA extracted from cultures treated as indicated. β-actin amplification was used to confirm comparability of the samples. The ethidium bromide-stained agarose gels of PCR products are shown. Data are representative of 2 independent experiments. (B) Equivalent amounts of protein lysates were analyzed by Western blot with anti-OPG MoAb. A representative of 2 separate experiments is shown. Equal loading of protein in each lane was confirmed by staining with the antibody to tubulin.