Healthy nonsmokers were grouped based on MUC5AC gene expression in 10-12
order brushed airway epithelial cells. Shown is data for n = 60 nonsmokers divided into nonsmoker “high MUC5AC expressors” (MUC5AC expression, highest quartile of all healthy nonsmokers, n = 15, upper shaded region) and nonsmoker “low MUC5AC expressors” (MUC5AC expression, lowest quartile of all healthy non-smokers, n = 15, lower shaded region). Expression of 5 endogenous control genes (ACTB, GAPDH, B2M, RPLP0 and PPIA) in the same samples are used as controls to assess the expression variability in nonsmokers of housekeeping genes compared to MUC5AC. The coefficients of variation (CV) of MUC5AC and endogenous control gene expression are shown.