DNA damage proteins increase in PHN rats. Immunostaining for p53 (a), p21 (c), and phosphorylated CHK-2 (e) was not detected in control rats injected with normal sheep serum. In contrast, p53 (b), p21 (d), and phosphorylated CHK-2 immunostaining (f) increased in Sprague-Dawley rats with PHN (arrows indicate positive-stained podocytes). g The results of Western blot analysis performed on isolated glomerular protein from control and PHN rats. In PHN animals, the levels for phosphorylated (phos) CHK-1 and CHK-2, p53, p21, and GADD45 increased compared with controls. The housekeeping proteins, actin and tubulin, were used to ensure equal protein loading.