Figure 3.

BMP4 induction of differentiation toward squamous cells. A. From left to right: 1^st column - representative BMP4 immunohistochemistry staining (positive cells are shown in red), 2^nd column - immunofluorescence staining of BMP4 (red), 3^rd column - immunofluorescence staining of squamous cell marker keratin 6 (KRT6, green), 4^th column – overlap of 2^nd and 3^rd column. These staining were performed on the human airway epithelium of nonsmoker with normal morphology (1^st row), asymptomatic smoker (2^nd row) and COPD smokers (3^rd and 4^th rows) with abnormal morphology. Nuclei are stained with DAPI (blue). Scale bar - 20 μm. The biopsy images with immunohistochemistry and immunofluorescence staining in each row were from the same sample. B. TaqMan assessment of fold-change (log₂) in the expression of squamous cell-related genes (IVL, KRT14, KRT6A, KRT6B and SFN) from the airway epithelium after 14 days ALI culture with BMP4 (10 ng/ml) stimulation from the basolateral side vs untreated control. * p<0.05, ** p<0.01, *** p<0.001, n=3 or 4. C. Immunofluorescence top staining of the squamous cell marker KRT14 (red) on the airway epithelium after 14 days ALI culture with BMP4 (10 ng/ml) stimulation from the basolateral side (right) vs untreated control (left). Nuclei are stained with DAPI (blue). Scale bar – 20 μm.