Immunofluorescence for SOD3 and EPO protein in kidneys of animals exposed to hypoxia for 6 hours. (A) Confocal laser scanning micrograph of histologic sections of Wt kidney stained with antibody against SOD3. Renal sections were visualized with FITC-conjugated secondary antibody. SOD3 stained as brilliant green immunofluorescence in the proximal tubules; faint labeling is seen in the glomeruli and other tubules. (B) Confocal micrograph of Wt kidney stained for EPO using Cy3 secondary antibody. EPO stained as brilliant red fluorescence in the proximal tubules of the cortex. No staining was observed in glomeruli, distal tubule cells, or medulla. (C) Dual-labeling immunofluorescence of SOD3 with FITC (green) colocalizing with EPO Cy3 (red). Overlay of images in panels A and B reveals colocalization of SOD3 and EPO proximal tubule (yellow fluorescence). (D) KO kidney shows negligible SOD3 expression. (E) KO kidney shows EPO expression. Asterisk (*) denotes proximal tubules (original magnification, × 650).