By contrast, using differentiated primary human airway epithelia cultures at the air-liquid interface from healthy individuals, Buonfiglio et al. reported a decrease in CYP27B1 mRNA expression upon treatment with cigarette smoke extract as did Mulligan et al. when using primary sinonasal epithelial cells from healthy subjects and patients with chronic rhinosinusitis [22, 23]. The gene discussed is CYP27B1; the disease is chronic rhinosinusitis.