NPY4R is a receptor for neuropeptide Y and peptide YY. The rank order of affinity of this receptor for pancreatic polypeptides is PP, PP (2-36) and [Ile-31, Gln-34] PP > [Pro-34] PYY > PYY and [Leu-31, Pro-34] NPY > NPY > PYY (3-36) and NPY (2-36) > PP (13-36) > PP (31-36) > NPY free acid. NPY4R is a useful epigenetic marker for oropharyngeal cancer, where methylation of the NPY4R promotor correlates with poor prognosis. Separately, copy number variations in NPY4R are associated with waist circumference and body mass index in women. In immunohistochemistry, NPY4R has generally low membranous and cytoplasmic positivity that is strongest in the gastrointestinal tract, and it is also found in the central nervous system, endocrine tissues, the lung, gallbladder, pancreas, kidney, bladder, skin, reproductive tissues, and immune tissues. References: Oncotarget. 2017 Sep 29; 8(44): 76318–76328, PMID: 29100314; PLoS One. 2018 Apr 5;13(4):e0194668, PMID: 29621259