In line with this notion, an array of mRNAs encoding cytokines and growth factors are detected in KS lesions, including TNF-α, TNF-β, IFN-γ, IL-1β, IL-6, platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) (11–13 and reviewed in9). This evidence concerns the gene IL1B and Kaposi's sarcoma.