SMAD4 and cancer: The requirement for SIRT7 inSIRT1-dependent EMT promotion might also be relevant for understanding theobservation that in contrast to the EMT- and metastasis- promoting effects of SIRT7reported in prostate cancer cells23, other work reported that inbreast cancer cells, SIRT7 suppresses EMT and tumor metastasis via deacetylation ofthe Smad4 transcription factor28.