Fig. 2. Stage-dependent induction of phenotypic reversion by JNK inhibition. (A) BMMs were cultured with M-CSF (30 ng/ml) plus RANKL (100 ng/ml). After 2 or 3 days, SP600125 (+SP) or vehicle (–) was added and cells were further incubated for 24 hours before TRAP staining. pOCs were also stained for comparison. (B) RAW264.7 cells were cultured with RANKL (100 ng/ml). Cells were treated with SP600215 at the indicated day or vehicle at day 2 for 24 hours and were then stained for TRAP. (C) RAW264.7 cells cultured with RANKL (100 ng/ml) for 2 (left) or 3 (right) days were transfected with wild type (WT) or dominant negative (DN) JNK. Cells were further incubated with RANKL for 24 hours and the percentage of TRAP⁺ cells was determined. Data are the mean ± s.d. and are representative of three independent experiments.