CD34 and myeloproliferative neoplasm: To ascertain the effects of the CCL2-CCR2 axis in PMF hematopoietic progenitors, we incubated for 24 h PMF CD34+ cells with rhCCL2 to test the activation of downstream signaling cascades related to cell proliferation and differentiation, as well as relevant for MPN, namely JAK/STAT, Akt and MAP-kinase pathways.