Oncogenic c-Kit receptor tyrosine kinase “driver” mutations have been identified in a number of cancers, such as acute myeloid leukemia (AML), melanoma, in mast cell leukemia, and in gastrointestinal stromal tumors (GIST) [33], and tyrosine kinase inhibitors (TKIs), such as imatinib or sunitinib, with activity against c-Kit routinely used in the treatment of these cancers. The gene discussed is NTRK1; the disease is mast cell leukemia.