Additionally, the epithelial cell marker Cystic Fibrosis (CF) Transmembrane Conductance Regulator (CFTR), which plays also a role in the pathogenesis of CF [24], has been determined on the surface of 2D- and 3D-differentiated AEC2 in this study (Figs. 5 and 6). This evidence concerns the gene CFTR and cystic fibrosis.