Btbd7 expression induced by fibronectin regulates Snail2 expression and is required for branching morphogenesis. (A) mRNA expression of fibronectin, Btbd7, Snail2, and E-cadherin in cleft versus bud epithelia by qPCR. (B) Induction of Btbd7 and Snail2 expression after fibronectin addition to isolated salivary epithelium by qPCR. (C) Effects on epithelial expression of Btbd7 and Snail2 by siRNA knockdown of each gene. (D) Effect of Btbd7 siRNA knockdown in salivary gland organ culture and quantification of numbers of buds per gland (E; n=8). (F) Total bud volume after siRNA transfection. (G) Effect of Btbd7 siRNA knockdown in embryonic lung with quantification of branches (H; n=15). Scale bar, 100 µm. *P<0.05, **P<0.01, ***P<0.001. Error bars, s.e.m.