text: 12577361_5	Immunohistochemical examination conducted in 2 rats showed that the short spindle-shaped interstitial cells were expressed positively both by vimentin and proliferative cell nuclear antigen (PCNA), but were shown negative for smooth muscle actin (SMA) and p53; (3) At month 6, the occurrence of renal tumor in the three dosage groups was 42.8%, 25.0% and 0% respectively, including 4 cases of renal mesenchymal tumor and 1 case of nephroblastoma.