Fig. 6.

Regional location of Cxcr4 in the adult kidney. A: immunohistochemistry for Cxcr4 in the cortex (top), medulla (middle), and papilla (bottom). As shown, Cxcr4 was widely distributed in the kidney parenchyma. Kidney sections incubated with identical amounts of irrelevant rabbit IgG and simultaneously processed with those with the Cxcr4 antibody gave no signal (not shown). Bars = 50 μm. B: representative immunoblot for Cxcr4 and GAPDH in different regions of the kidney. C: relative abundance of Cxcr4 vs. GAPDH in different regions of the kidney showed that the papilla had a significantly greater amount of the ∼ 45-kDa monomeric form of Cxcr4 than both the cortex and the medulla (*P < 0.05). Data derive from samples of 8 individual experiments, where protein homogenates from the 3 different regions of the kidneys were simultaneously analyzed. Each lane for Cxcr4 contained 24 μg of protein homogenate. Because of the large signal obtained with the antibody to GAPDH, for proper quantification of this protein's abundance in the sample, only one-third (i.e., 8 μg) of the protein homogenates were loaded on the gels.