PDGFRA and gastrointestinal stromal tumor: Important, molecular and genomic changes in IM-resistant GISTs illustrated that the PI3K/Akt/mTOR pathway has a greater importance in IM-resistant GIST than other pathways downstream of c-KIT or PDGFRA (e.g., MEK/MAPK pathway), therefore illustrating a rationale for targeting the PI3K/Akt/mTOR pathway in GIST [6].