[Gastrointestinal stromal tumor].

Gastrointestinal stromal tumors (GISTs), the most common submucosal tumor in the gut, express the KIT protein. Gain-of-function mutations in the KIT or PDGF-R alpha gene is involved in oncogenesis and growth of GISTs. Although the first-line therapy of resectable GISTs is surgery, imatinib mesylate, a target-based molecule against KIT and PDGF-R alpha proteins, showed remarkable clinical effects and good tolerability for non-resectable GISTs. Now, imatinib is in the first-line for non-resectable GISTs. Resistance against imatinib, however, is proved after long-standing use of the drug.