The appreciation of the uniform involvement of the JAK-STAT signaling pathway in MPN promoted the development of a new class of drugs, the JAK inhibitors, which although lacking selectivity against the mutated protein have nonetheless dramatically changed the life of patients, particularly MF and PV, and may be also carrying some advantages in terms of survival (MF) and reduction of thrombotic events, the leading cause of morbidity and mortality in PV. The gene discussed is SOAT1; the disease is myeloproliferative neoplasm.