KIT and gastrointestinal stromal tumor: Moreover, approximately 75% of GISTs have a mutation in KIT occurring in exons 9 (8%), 11 (90%), 13 (1%), and 17 (1%), and 10% to 20% of GISTs have a mutation in platelet-derived growth factor receptor A (PDGFRA) occurring in exons 12, 14, and 18 [8, 9], which encode type III receptor tyrosine kinase and are the cornerstone for the receptor tyrosine kinase inhibitors (RTKIs) applied in GIST patients [10].