Fig. 8. Wnt5a and Wnt5b have opposite activities in regulating Sox9-controlled Col2a1 expression. (A) Sox9 protein was examined by immunohistochemistry. Sox9 protein level was decreased in both Wnt5a^-/- and Col2a1-Wnt5a mice. No change was detected in Col2a1-Wnt5b mice. (B) The expression of Col2a1, a direct target of Sox9, was decreased in Col2a1-Wnt5a mice but increased in Wnt5a^-/- and Col2a1-Wnt5b mice. (C) Col2a1 reporter activity was decreased by Wnt5a and increased by Wnt5b in primary chondrocytes in a dose-dependent manner. The histograms are presented as the mean±s.d. from three independent experiments. (D) Col2a1 reporter and mutant Col2a1 reporter that lacks Sox9-binding sites could not be activated by TCF1. But Wnt1 inhibited the Col2a1 reporter.