Dermo1-Cre reduces NFI-B expression in Nfibflox/flox lungs in mesenchyme, but not in epithelium. Lung sections from E16.5 Nfibflox/flox (A) and Nfibflox/flox, D1-Cre (B) embryos stained for NFI-B showed Dermo1-Cre eliminated almost all NFI-B in mesenchyme at E16.5. Immunostaining for NFI-B (C, D) in E18.5 Nfibflox/flox and Nfibflox/flox, D1-Cre lungs reveals Dermo1-Cre eliminated NFI-B expression throughout the lung mesenchyme at E18.5 but didn’t affect NFI-B expression in the epithelial cells (arrows). Insets show a 5X magnification. Arrows denote NFI-B in bronchiolar epithelial cells and the region of magnification; Scale bar, 50 µm.