The p55PIK specific inhibitor, TAT-N24, can abrogate the resistance of GIST cells to Imatinib [32] and dramatically down-regulated KIT expression and enhanced the Imatinib effectiveness in an NF-κB -dependent manner as validated in the PDX tissue from IM-resistance-GIST patients. Here, PIK3R3 is linked to gastrointestinal stromal tumor.