In the human breast cancer cell lines, we showed that Smad3 binding to known target sites in the promoters of the SMAD7, COL7A1, and SERPINE1 genes in M3 cells was maximal by 1 hour after TGF-β addition, so this time point was selected for the ChIP-chip analysis (Figure 2C). This evidence concerns the gene COL7A1 and breast cancer.