SMAD4 and breast neoplasm: In addition, the expression levels of p-Smad2, p-Smad3, and Smad4 in the nucleus of MCF-7 breast tumor cells were measured by immunofluorescence microscopy, and we found that SSA could reduce the level of p-Smad2/3 in the nucleus with or without the presence of TGFβ1(Figure 6b).