Prolactin receptor (PRLR) is a cytokine receptor, encoded by a gene located on chromosome 5p13-14, that interacts with prolactin as a transmembrane receptor.PRLR consists of an extracellular region, a transmembrane region, and a cytoplasmic region that binds prolactin.PRLR is widely expressed in mammary glands, placentas, kidneys, livers, and pancreases, and, in addition to prolactin, it is also activated by growth hormone (GH) and human placental lactogen (hPL) activation. Studies have shown that abnormalities in PRLR are closely associated with the development and prognosis of certain tumors, especially breast cancer. Specific binding to PRLR stimulates breast cancer cell growth, and antagonists that bind to PRLR but do not dimerize it inhibit breast cancer cell growth.Several isoforms of PRLR exist, including soluble PRLR, which does not transduce prolactin signaling.