NOS1, inducible NOS (NOS2) and NOS3 have been found in human mast cell (HMC)-1 cell line, NOS3 has been found in rat basophilic leukemia RBL-2H3 cell line and NOS2 is expressed in P815 mouse mastocytoma cell line. The gene discussed is NOS3; the disease is acute basophilic leukemia.