All MPN driver mutations (JAK2V617F, MPLW515L/K, CALR mutations) activate the cytokine/receptor JAK2 pathway and its downstream signaling such as the Signal transducer and activator of transcription (STAT1, 3 and 5), phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR and the MAPK/ extracellular signal-regulated kinase (ERK) pathways. The gene discussed is JAK2; the disease is myeloproliferative neoplasm.