Mean methylation levels of CG distributions in target regions. The upstream region was defined as the 2 kb upstream of the TSS, and the downstream region was defined as the 2 kb downstream of the TTS. Data analysis results shown that sequencing depths were observed increase in areas that were closer to gene regions. Each region of the two parts was divided equally into 20 sections. Moreover, the first, internal and terminal exons each shared 10 sections. Each methylation level that was reported represented the mean value of the corresponding section.