Cell cultures composed of characteristic spindle-shaped tumor cells have been established from KS lesion explants by the addition of cytokines like TNF-α, TNF-β, IFN-γ, IL-1, IL-6, GM-CSF and oncostatin M [1],[2],[9],[10] highlighting the role of these paracrine factors in KS lesion cell survival. This evidence concerns the gene OSM and Kaposi's sarcoma.