Oncogenic mutations of KIT identified in malignancies such as mastocytosis and GISTs can be autoactivated without ligand stimulation, and the ligand-independent activation of KIT mutations is dependent on the PI3 kinase association with KIT, loss of PI3 kinase association dramatically inhibits the ligand-independent activation of KIT mutations [27, 28]. The gene discussed is KIT; the disease is mastocytosis.