Furthermore, another individual up-regulated proteins in our study have already been identified as metastatic markers in other types of cancer by using proteomics methods, these were PA28 (proteasome activator alpha) implicated in ovary cancer [19], α-enolase in hepatocellular carcinoma [20], triosephosphate isomerase in lung squamous carcinoma [21] and PGK1 in gastric cancer [22]. Here, PGK1 is linked to gastric cancer.