Prolactin is secreted not only by anterior pituitary gland, but also by immune cells and it was shown that it can stimulate the immune cells by binding to prolactin receptors.[3] Prolactin receptors were exclusively expressed on fibroblast like synovial cells and lymphocytes infiltrating into the synovium in patients with RA.4 It has demonstrated that PRL can enhance RA synovial cell proliferation. Here, PRLR is linked to rheumatoid arthritis.