PTGS2 and Kaposi's sarcoma: Similar to the involvement of COX-2/PGE2 in cytokine secretion in many inflammation related diseases [62], KSHV induced COX-2 also plays important roles in the expression and secretion of various chemokines, growth and angiogenic factors and thereby controls the angiogenesis and tube formation (Figure 7, S7, and S8) events of KS pathogenesis.