For example, the free fatty acid receptor 2 (FFAR2, also known as GPR43) and free fatty acid receptor 3 (FFAR3, also known as GPR41) that sense short-chain fatty acids (SCFAs), were lowly expressed in all cell types, whereas the FFAR4 (also known as GPR120) that senses medium- and long-chain unsaturated fatty acids, was highly expressed in the GC and SC and some subtypes of BC in forestomachs. This evidence concerns the gene FFAR2 and breast cancer.