In searching for the identity of the oncogenic KS progenitor, we reasoned that if KSHV evolved its molecular machinery to activate PDGFRA signaling, a plausible oncogenic progenitor should be a pluripotent cell where PDGFRA plays a major proliferative and survival role, such as mesenchymal stem cell (MSC) [30]. This evidence concerns the gene PDGFRA and Kaposi's sarcoma.