MIF immunohistochemistry in the bladder and prostate. The bladder showed strong MIF immunostaining in the urothelium (Fig 1A,1B). The superficial layer of the urothelium had weak MIF immunostaining with some areas devoid of stain (Fig 1B; arrowheads), whereas the deeper layers of the urothelium showed intense MIF staining (long arrows). The fibroblasts immediately under the urothelium also exhibited MIF staining (arrow with asterisk). The smooth muscle of the bladder also showed MIF immunostaining (Fig. 1C) in the cytoplasm of muscle fibers and in nuclei. In the prostate, intense MIF immunostaining was observed in the acini (Fig 1D,1E,1F). Epithelial cells in the proximal acini showed strong MIF immunostaining (Fig 1D,1E) and the smooth muscle surrounding those acini also showed MIF immunostaining (Fig 1E; long arrows). However, in central and peripheral acini, only basal epithelial cells showed MIF immunostaining (Fig 1E, arrowhead; F, long arrows). bv = blood vessel. Calibration bar: A,D = 200 μm; B,C,E,F = 100 μm.