SMAD3 and breast cancer: HDAC inhibitors may affect the expression/activity of other transcription factors known to regulate ZFP36 transcription such as Smad3, Smad4, AP1, c-myc or NFκB [23,31,40,41] but also some microRNAs, such as miR-29a, which downregulates TTP in a breast cancer model [42] and is known to be upregulated in colon cancer [43].