Histological analyses of IQ1 treated lungs. (A) TOPGAL, the Wnt signaling reporter mouse shows activation of β-catenin/LEF/TCF reporter by expression of β-galactosidase. E12.5 lung explants of TOPGAL mouse were treated with either DMSO (control), IQ1 (10 μM) or ICG-001 (10 μM) for 48 hours. β-galactosidase (blue) activity is observed in the bronchial epithelium of the proximal airway (arrows). IQ1 did not decrease β-galactosidase activity, whereas ICG-001, a known CBP/catenin antagonist, decreased β-galactosidase activity in the proximal airway. (B) Immunohistochemistry shows localization of β-catenin at the cell membrane of epithelial cell (arrows) and mesenchymal cells. (C) Whole mount PECAM-1 staining (brown) shows capillaries around the distal tips. Four days of IQ1 treatment in utero did not significantly disrupt formation of capillaries as judged by PECAM staining.