KIT and gastrointestinal stromal tumor: Mutations in KIT gene are present in 85% of gastrointestinal stromal tumors (GISTs), commonly at exon 11, which confers increased sensitivity to imatinib, a KIT tyrosine kinase inhibitor, and at exon 9, which confers increased sensitivity to sunitinib, a vascular endothelial growth factor receptor inhibitor which also targets KIT [63].