MAPK1 and gastrointestinal stromal tumor: Mutant Kit (Kit(mut)) transforms a precursor of ICC through permanent activation of the PI3K–Akt pathway, STATs and Erk resulting in development of GIST.15, 16, 17, 18, 19, 20, 21 GIST cells can then proliferate autonomously due to the anti-apoptotic effect and cell cycle progression by Kit signals.17, 18, 19, 20, 21 PDGFRα(mut) also causes GIST (~5%) in this way.22, 23 Ten percent of GISTs have no mutation either in Kit or PDGFRα. 23, 24