Sclerostin restores the expression of anabolic markers by inhibiting the c-Jun N-terminal kinase in chondrocytes. (A) Western blot analysis of the activation of c-Jun N-terminal kinase (JNK) and protein kinase C (PKC) pathways with Wnt3a and sclerostin (n = 3). (B) Active Rho pull-down and detection (n = 3). (C) Alcian blue staining and spectrophotometric quantification of highly sulfated glycosaminoglycans (GAGs). Bar, 100 nm (n = 7). (D) Sclerostin fully restored the gene expression of anabolic markers with treatment with the JNK inhibitor SP600125, but not the PKC inhibitor staurosporine (n = 7). (E) Sclerostin alone was sufficient to inhibit the increased gene expression of catabolic markers (n = 7). (F) Sclerostin inhibited the Wnt3a-increased gene expression of WNT5A and WNT10B (n = 9). (G) Western blot analysis of the activation of JNK, CaM kinase (CaMK) and PKC pathways with Wnt3a and sclerostin (n = 3). (H) Sclerostin rescued Wnt5a-inhibited gene expression of anabolic markers (n = 3). Wild-type chondrocytes were used for all the experiments. Data are mean ± SEM. *P < 0.05 versus controls; £P < 0.05 versus Wnt5a.