Therefore, SCFA have paradoxical effects on cell proliferation and apoptosis in in vivo and in vitro studies, as they show stimulative proliferation effect in in vivo of normal gut [30, 31], whereas display inhibitive proliferation effect in tumor cells owing to the Warburg effect, which makes SCFA function as HDAC inhibitors, and thereby inhibit proliferation [32]. This evidence concerns the gene HDAC9 and neoplasm.