Kinetics of DNA methylation after TGF-β treatment. a. Huh7 and HepG2 cells were exposed to TGF-β for shorter time points (1 to 4 days), followed by DNA extraction, bisulfite modification, and pyrosequencing analysis of one CpG site in the body of TRRAP gene (a DMP showing hypermethylation in response to TGF-β, as seen in Figure 3b). b. in a similar way, both cell lines were studied at longer time points after release from 4 days of TGF-β treatment. Cells were followed during 12 days post-release and displayed a rate of proliferation close to non-treated cells. (*) indicates P value < 0.05 relative to non-treated cells at the corresponding time point and cell line.