Fig. 7.

Mesenchymal FGF and WNT/β-catenin signaling requires both FGF9 and WNT inputs to maintain FGF9 responsiveness. (A-L) Lung explant cultures from control (A-C,G-I) and Fgf9^–/– (D-F,J-L) mouse embryos were untreated (A,D,G,J) or treated with LiCl (B,E,H,K) or BIO (C,F,I,L). Control and Fgf9^–/– explants were also treated with FGF9 (G-L). Red lines indicate mesenchymal thickness. Scale bar: 200 μm. (M) Quantification of mesenchymal growth in response to LiCl, BIO and FGF9 (n=3 explants for each condition). Dashed red line shows mesenchymal thickness of wild-type lung explants. Error bars represent s.d. ^*P<0.05, ^**P<0.01, ^***P<0.001, Student's t-test.