<qa>  What is the cytokine in the pathogenesis of KS?This is a phase II study to determine the activity of bevacizumab, a putative antiangiogenic agent, in Kaposis sarcoma KS. Bevacizumab is a humanized recombinant antibody to vascular endothelial cell growth factor VEGF, an important cytokine in the pathogenesis of KS. 