INSL3: ProductsINSL3 (insulin-like 3), formerly called Ley I-L (Leydig cell insulin-like), is a member of the insulin/relaxin superfamily. INSL-3 is a secreted protein produced by testicular Leydig cells and in lower amounts by ovarian follicular theca interna cells and the corpus luteum. The receptor for INSL-3 is the leucine-rich G-protein coupled receptor LGR8, also called RXFP2 or GREAT. Deletion of either INSL3 or LGR8 in the mouse causes failure of the testes to descend (cryptorchidism). Mutation of INSL3 is also an occasional cause of cryptorchidism in humans.