PIK3R3 and gastrointestinal stromal tumor: We analyzed mutations of the KIT gene, expression of p55PIK and KIT, and phosphorylation of NF-κB p65 (Ser536) in surgically-dissected tumor samples before and after Imatinib treatment from 8 GIST patients (the initial Imatinib treatment of these patients are positive response, detailed information about the patients are shown in Supplementary Table S1).