CXCL1 and myeloproliferative neoplasm: CD56+CD14+ monocytes are known to be a pro-inflammatory subset of monocytes,25 increased levels of which have been found in patients with solid tumors and hematological malignancies.26 These data suggest a role for CD56+CD14+ monocytes in creating a high GRO-α environment which may in turn be a driver of MPN disease evolution.