An endogenous strain of the mouse microbiota (Faecalibaculum rodentium isolate PB1) and its human counterpart Holdemanella biformis belonging to the Erysipelotrichaceae family, which disappear during the early phases of colorectal tumorigenesis, produce short-fatty acids that block tumor cell proliferation by reducing activation of nuclear factor of activated T cells, cytoplasmic 3 (NFATc3) and calcineurin (16). Here, NFATC3 is linked to neoplasm.