Fig. 3.

Multiple signaling pathways regulate the expression and activity of Sox9 during chondrogenesis. Signals that are known to activate Sox9 expression or activity are shown in green The signals that inhibit Sox9 expression are shown in red. Sox9 and some of its downstream targets are indicated in black. See text for details. BMP, bone morphogenetic protein; Col2a1, collagen, type II, α1; FGF, fibroblast growth factor; PKA, protein kinase A; Shh, sonic hedgehog; TGFβ, transforming growth factor β.