Some of these 3N cases, however, have been found to harbor mutations in genes such as CBL and SH2B3/LNK (62, 63), which confer enhanced JAK2 activity by removal of inhibition; hence it is likely that all Ph-negative MPN cases include constitutive JAK2 activity in the malignant clone (60). The gene discussed is SH2B3; the disease is myeloproliferative neoplasm.