In lung cancer, there is a little or no methylation of genes commonly methylated in other cancers, such as ARF, CDKN2B, CTTNB1, MLH1, and RB1. The hypermethylated genes in lung tumors such as APC, CKDN2A (encodes p16INK4A and p14arf), CHD13, RARB, and RASSF1A may be considered as tumor suppressors [65,88]. Here, RARB is linked to lung cancer.