Figure 4. Sunitinib inhibits Renca tumor growth, which corresponds to p-STAT3 reduction.

(A). Left, sunitinib inhibits Stat3 activity in cultured Renca tumor cells. Tumor cells were treated (2 h) with sunitinib at indicated concentrations and cell lysates were then used for western blot analysis. Right, sunitinib inhibits Renca tumor growth. BALB/c mice were implanted s.c. with Renca cells (2.5 × 10⁶). Sunitinib or vehicle control was administered orally, once daily, at the indicated doses, 7 days after tumor challenge; data are mean ± s.e.m, p<0.01, n=6. (B). Sunitinib inhibits phospho-Stat3 (p-Stat3) protein level (left) and reduces Cyclin E and Survivin expression (right) in Renca tumors. Western blot analyses of tumor tissues harvested 10 days after sunitinib treatment, using indicated antibodies.