IL1B and Kaposi's sarcoma: AIDS-KS spindle cells are stimulated to secrete VEGF by platelet-derived growth factor (PDGF)-beta and interleukin (IL)-1 beta, and co-injection of these two factors increases the vascularity of KS-like lesions in mice.15 VEGF acts as an autocrine growth factor in KS, which has high levels of VEGFR1, VEGFR2,16 and VEGFR317 compared with adjacent normal skin.