Compared with the normal gastric mucosa, the expression levels of PAK2 (IRS for gastric cancer vs. normal gastric mucosa: 5.62 ± 1.93 vs. 2.33 ± 0.68, P < 0.001) and pSer20PAK2 (IRS for gastric cancer vs. normal gastric mucosa: 5.99 ± 2.06 vs. 2.27 ± 0.61, P < 0.001) proteins were both significantly increased. This evidence concerns the gene IARS1 and gastric cancer.