In addition, although methylation of several genes, such as RARβ, TIMP-3, p16INK4a, DAPK, p14ARF, and GSTP1, are frequently occurred in NSCLC, correlations between methylation changes of these genes in NSCLC tumors and the clinical data are different at different stages (stages I to III) [27]. Here, GSTP1 is linked to non-small cell lung carcinoma.