Plasma levels of endostatin, GDF15, matrix metallopeptidase 9 (MMP9), PTX3, endothelial selectin (E-selectin), platelet selectin (P-selectin) and soluble VEGF receptors (sVEGFR) 1 and 2 were determined by ELISA and compared between ET patients and healthy controls. The gene discussed is MMP9; the disease is essential thrombocythemia.