Constitutive Activation of STAT3 in Malignant and Nonmalignant Cells Drives Aberrant Cytokine Secretion in MPN.Stat3 deletion in a MPN mouse model bone marrow cells normalizes the production of cytokines, recapitulating the therapeutic effects of JAK inhibition therapy with ruxolitinib. In contrast, selective tumor-specific deletion of Stat3 fails to abrogate cytokine production, indicating that JAK inhibition in both malignant and nonmalignant populations is required for therapeutic efficacy.Reprinted from Cancer Discovery, 2015, 5/3, 316-331, M. Kleppe et al, JAK-STAT Pathway Activation in Malignant and Nonmalignant Cells Contributes to MPN Pathogenesis and Therapeutic Response, with permission from AACR.