SMAD2 and neoplasm: CCL7 activates the TGF-β pathway by enhancing Smad2 phosphorylation, and blocking the TGF-β pathway markedly inhibits the effects of CCL7 on tumor migration and invasion, highlighting the role of CCL7 in regulating tumor progression by influencing the tumor microenvironment via the TGF-β pathway (Liu et al., 2016).