We assessed expression of PD-1 following stimulation of healthy control NK cells with pro- or anti-inflammatory molecules, growth factors or angiogenic factors previously reported to play a role in KS pathogenesis, such as IL-1β, IL-6, IL-10, TGFβ, VEGF or prostaglandin E2 (PGE2). The gene discussed is PDCD1; the disease is Kaposi's sarcoma.