FFAR2 and breast cancer: In metastatic cancer, the activation of receptors for SCFAs (such as propionate and butyrate), specifically free fatty acid receptors (FFAR2 and FFAR3), inhibits the invasive phenotype of breast cancer cells, thereby suppressing metastasis.373,391 These receptors play a crucial role in modulating inflammation and the production of leptin,374 stimulating insulin secretion in response to glucose,375 the secretion of glucagon-like peptide-1,376 and the production of peptide YY.378 Multiple studies have indicated that FFAR2 and FFAR3 are involved in tumor suppression.