 Mutation of c-kit causes the constitutive activity of tyrosine kinase, which results in cancerous gastrointestinal stromal tumors.Results of c-kit mutation include unrestricted tyrosine kinase activity and cell proliferation, unregulated phosphorylation of c-kit, and disruption of some communication pathways.Therapy with imatinib can inhibit the non-normal cell signaling mechanisms in gastrointestinal stromal tumors.