Fig. 4.
p16INK4a expression and interstitial cell differentiation in control mice and in response to 7 days of UUO. A and B: double labeling for p16INK4a and 5′-nucleotidase (NT) demonstrating p16INK4a expression in cortical fibroblasts. 5′-NT expression is markedly diminished following UUO. C and D: double labeling for p16INK4a and α-SMA demonstrating p16INK4a expression in α-SMA-positive myofibroblasts following UUO. α-SMA is only expressed in vascular smooth muscle cells, and p16INK4a-positive interstitial cells in control kidneys are α-SMA negative (arrowheads). E and F: double labeling for p16INK4a and PNA showing increased p16INK4a expression in outer medullary collecting duct cells following UUO. Original magnification ×400.