A, Representative confocal images of Spns2 in primary cultures of human nasal epithelial cells (hNAEc), cigarette smoke extract-treated (CS) vs. control (C). B, Measurement of Spns2 mean fluorescence intensity (MFI) in hNAEc; **, p = 0.001 significant reduction in CS-treated cells, data pooled from 2 experiments. C, Representative confocal images of Spns2 in 16HBE cell line, treated with CS vs. control. D, Measurement of Spns2 mean fluorescence intensity (MFI) in 16HBE cells; ***, p<0.001 significant reduction in CS-treated cells, data pooled from 2 experiments. Red: Spns2; Green: cyto-keratin (epithelial-specific marker) in A, and β-actin in C. Scale bar = 20μm.