SMAD2 and breast carcinoma: Dedicator of cytokinesis 1 (DOCK1) down-regulates Claudin through ribosomal RNA processing 1B (RRP1B)/DNA methyltransferase (DNMT) to promote the growth and migration of breast cancer cells (102); Claudin through down-regulates the transforming growth factor-β(TGF-β)/Smad2/DNMT to promote EMT, metastasis and invasion of breast cancer cells (103).