PIK3R3 and gastrointestinal stromal tumor: Results showed that expression of p55PIK was not changed; however, the expression of KIT and NF-κB pp65 (Ser536) was decreased, indicating that p55PIK signaling blockade inhibited the NF-κB signaling and KIT expression, which in turn, led to inhibition of tumor growth of IMA-resistance-GIST in vivo.