Total RNA was isolated from GC tissues by TRIzol (Invitrogen) according to the instructions. Reverse transcription of total RNA was carried out with PrimeScript RT reagent kit (TAKARA Biotechnology (Dalian) Co., Ltd) on PCR amplifier under the following conditions: 37°C for 15 min, 85°C for 5 seconds. After that, cDNA was tested in real-time qPCR on the CFX96 Real Time PCR System with the use of Premix Ex Taq (SYBR and probe qPCR, TAKARA Biotechnology (Dalian) Co., Ltd) under the following conditions: 95°C activation for 30 seconds, 95°C denaturation for 5 seconds, 60°C annealing and elongation for 30 seconds, which repeated for 40 cycles. The results were recorded with CT value. After comparison of amplification efficiency, Livak method (2−ΔΔCT) was used to compare the difference between GC tissues and corresponding adjacent normal gastric tissues, in which GAPDH was used as reference gene and corresponding adjacent normal gastric tissues were applied as calibration control. All the sequences of primers and probes of these genes were designed and synthesized by TAKARA Biotechnology (Dalian) Co., Ltd (Table 6).