Microarray of mouse MPN revealed reduced expression of X-linked inhibitor of apoptosis (Xiap) and mitogen-activated protein kinase 8 (Mapk8) in JAK2V617F relative to JAK2WT cells, which were normalized by TNFR2 but not TNFR1 blockade. Here, MAPK8 is linked to myeloproliferative neoplasm.