However,subtherapeutic concentrations of butyrate (less than 0.5 mM) have received littleattention in antitumoral research due to their perceived lack of anticancer action.Nonetheless, previous reports have shown that treatment with less than 0.5 mM ofbutyrate can induce ligand-independent transcription of prostatic-specific antigenin a prostate cancer cell line (Sadar and Gleave,2000) and induce estrogen receptor alpha mRNA in a breast cancer cellline treated with a concentration of 0.3 mM of butyrate (DeFazio et al., 1992). Here, ESR1 is linked to breast cancer.