STAT3 and neoplasm: MDSCs can be classified into monocytic (CD11b+Ly6ChighLy6G−) and granulocytic MDSCs (CD11b+Ly6CintLy6Ghigh) based on their nuclear morphology and surface markers.3 In tumor-bearing individuals, IMC populations in bone marrow could respond to tumor-derived factors and proliferate through activation of JAK protein family and STAT3 signaling pathways.