Reactivity of an anti-rat FRβ mAb with rat lung and liver tissues. Lung and liver tissues from normal rats were stained using antibodies against CD68, FRβ, or E-cadherin. Photographs are representative of CD68-, FRβ-, and E-cadherin staining in lung or liver tissues of three rats per group. Note that FRβ-positive cells were observed in the liver but not in the lung. CD68- positive cells and E-cadherin-positive cells (indicating the presence of epithelial cells) were observed in both tissues; original magnification was ×400. FRβ, folate receptor β; mAb, monoclonal antibody.