SMAD2 and breast cancer: Given that SMAD effectors of TGF-β1 signaling can interact with DICER1 to promote primary miR-21 processing into precursor miR-21 [33], We hypothesize that overexpression of PICK1 disrupts the association of p-SMAD2 and p-SMAD3 with DICER1 and thus decreases the processing of pre-miR-615-3p to mature miR-615-3p in breast cancer cells.