CD8A and neoplasm: Both systemic and intratumoral butyrate impaired anti-tumor response in MC38 and B16F1 models.Intratumoral butyrate did not directly protect tumor cells from radiation but inhibited radiation-induced anti-tumor immune responses.Intratumoral butyrate inhibited type I IFN expression in dendritic cells and hence suppressed dendritic cell functions and activation of CD8+ T cell immune responses.