Berg et al. reported a low expression of ABCB1/MDR1 mRNA in the central and peripheral region of the lung from both healthy and chronic obstructive pulmonary disease (COPD) subjects [34]; the same author, however, more recently showed MDR1 protein expression in pulmonary lung epithelium, with more profound staining on the apical cell membrane of ciliated cells as well as in the bronchiolar epithelium [40]. The gene discussed is ABCB1; the disease is chronic obstructive pulmonary disease.