PECAM1 and Kaposi's sarcoma: In contrast, KS abnormal vessels were made of lined LANA-positive cells that were PDGFRA+, PDPN+ or PDGFRA+, PDPN- when stained with PDGFRA and PDPN antibodies; Nestin+, CD31+ when staining with Nestin and CD31 antibodies, and α-SAM+, VEGFR2+ when staining with α-SAM and VEGFR2 antibodies, suggesting that KS aberrant vessels are formed by KS tumor cells with hybrid M/E and xM phenotypes (Fig 2B).