Patients receive oral pazopanib once daily on days 1-28. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. Blood samples are collected at baseline and at 1, 4, and 8 weeks for correlative laboratory studies. Blood samples are evaluated for the following tumor markers by ELISA: VEGF, bFGF, sFLT-1, sTIE-2, sE-Selectin, VCAM-1, PDGF-AA, PDGF-AB and PDGF-BB. TSP-1 in plasma is measured by Accucyte™ competitive immunoassay.