A study of 10 postmenopausal female RA patients showed that an elevated prolactin/cortisol ratio early in the morning was accompanied by higher interleukin (IL)-1β and tumor necrosis factor-alpha (TNF)-α levels, suggesting that prolactin may be another mediator of the sex-related differences in RA [20]. The gene discussed is IL1B; the disease is rheumatoid arthritis.