Figure 1.

Expression of MDR related proteins in frozen sections of normal human lung tissue as detected with (A) C219 (anti-MDR1 P-gp), (B) P₃II-26 (anti MDR3 P-gp), (C) MRPr1 (anti-MRP1), (D1) M2II-12 (anti MRP2), (D2) M2III-6 (anti MRP2), (E) M₃II-9 (anti-MRP3), (F) LRP-56 (anti-MVP), (G) BXP-34 (anti-BCRP), and (H) control monoclonal antibody. MDR1 P-gp is present in the apical membrane of the bronchial and bronchiolar epithelial layer. MRP1 is present at the basolateral membrane of the bronchial and bronchiolar layer. Abberant MRP2 staining is only seen with M₂III-6. MVP is present in the cytoplasm of the bronchial and bronchiolar epithelial cells. Slides were stained with HRP labelled rabbit antimouse, FITC labelled tyramine, HRP labelled rabbit anti-FITC, and aminoethylcarbazole. BCRP, breast cancer resistance protein; FITC, fluorescein isothiocyanate; HRP, horseradish peroxidase; MDR, multidrug resistance; MRP, multidrug resistance protein; MVP, major vault protein; P-gp, P-glycoprotein.