Butyrate blocks the activity of class I and II HDACs and increases histone acetylation globally in multiple types of cells, including CD8+ T cells, B cells, hepatocytes, and some tumor cell lines, such as MCF-7 (human breast cancer cells) and HCT116 (human colon carcinoma cells) (Candido et al., 1978; Davie, 2003; Fellows et al., 2018; Luu et al., 2018; Ji et al., 2019; Sanchez et al., 2020). The gene discussed is CD8A; the disease is breast carcinoma.