Distinct effects of SMAD2 and SMAD3 were reported in breast cancer bone metastasis [8], pancreatic ductal adenocarcinoma cell proliferation and migration [9], HaCaT keratinocyte cell growth [10], TGF-β autoinduction in clostridium butyricum-activated dendritic cells [11] and TGF-β induced transcription [12]. Here, SMAD2 is linked to breast cancer.