Because treatment with insulin and IGF-1 results in a decrease in IR mRNA expression in human endometrial cells in vitro44, and because endometrial IGF mRNA and circulating IGF-1 protein levels are higher in PCOS patients than normal subjects45, it is likely that systemic insulin and IGF-1 work in a coordinated manner to regulate IRα and IRβ expression in the uterus. Here, IGF1 is linked to polycystic ovary syndrome.