EPC2-hTERT cells were used for ALI experiments (25 (link)). Cells were grown submerged in KSFM media on a 0.4 μm filter (Corning Life Sciences) for three days to reach confluency (protocol schematic, Figure 2A). Cultures were then switched to high-calcium concentration KSFM media (1.8 mM Ca++) for 5 days. Media was removed from the upper chamber to promote epithelial differentiation for days 7 to 10 (25 (link)).