Co-localization of TGF-β1 and iNOS in rat bladder. The confocal images show iNOS (red stain) and active TGF-β1 (green stain) in bladder sections. iNOS appears to be expressed at low levels in control male (Panel C) and female (Panel A) rats. In contrast, iNOS immunostaining is increased following treatment with CYP (Panels B and D). The red stain for TGF-β1 was mostly localized in the urothelium region of all the groups. This region was also marked by a lower degree of blue stain for smooth muscle actin/phalloidin in all the groups. Tissue destruction caused by CYP is prominent in Panel B and D relative to the normal tissue architecture observed in Panels A and C. The lumen region adjoining the urothelium is indicated by white arrows. Magnification is 60× in all sections. The experiment is representative of 5 fields per slide.