Studies [8, 9] have shown that GIST is caused by mutations of the protooncogene c-KIT (60%–80%) or the platelet derived growth factor receptor (PDGFRA) (10–20%), suggesting the use for tyrosine kinase inhibitors (TKI) like imatinib mesylate for treatment of patients with GIST. The gene discussed is KIT; the disease is gastrointestinal stromal tumor.