In order to verify if this event also occurs in pathologic cells that are phenotypically identical to VSELs (VSELs-like), we analyzed CD9 expression in HSCs and their supposed precursors, VSELs taken from the peripheral blood of patients newly diagnosed with myeloproliferative neoplasms, in comparison to those of healthy subjects. The gene discussed is CD9; the disease is myeloproliferative disorder.