Seeking a molecular explanation for the unique ability of K-hMSC growing in KS-like conditions to proliferate, and based on our results depicted in Figs 5 and 6 using mouse MSCs, we evaluated cyclin D1 expression and PDGFRA activation in human lymphatic endothelial cells and human mesenchymal stem cells infected with KSHV and exposed to the different media. The gene discussed is PDGFRA; the disease is Kaposi's sarcoma.