N humans, RXFP1 receptors are localized to the nipple, epithelial cells (Kohsaka et al., 1998), and stromal tissue (Ivell et al., 2003). Although relaxin has many well defined roles in reproduction in many species, in humans these effects are often absent or ill defined. Relaxin is produced in the human ovary during the luteal phase of the menstrual cycle and secreted into the circulation (Eddie e