Immunohistochemical staining with pimonidazole HCl, CD-31, Ki-67, and VWF in Caki-1 tumor tissue slices. Slices are shown from control animals and mice treated with sunitinib (40 mg/kg/day) for 5 days (top). Quantified staining data for the percent positive stained tissue. Data as mean ± SEM with **p < 0.01; ***p < 0.001 and n.s. for not significant.