Relaxin-2 is a peptide hormone structurally related to insulin, which is expressed in the placenta, decidua, prostate, and in the ovary during pregnancy. Of the three known relaxin genes, Relaxin-2 is the only relaxin known to circulate in the blood. Relaxin-2 binds specifically to the LGR7 and LGR8 receptors, previously identified as an “orphan” G protein coupled receptors. Signaling by Relaxin-2 through its target receptors enhances the growth of pubic ligaments and ripening of the cervix during birth. Recombinant Relaxin-2 is a nonglycosylated 6kD disulfide linked heterodimeric protein consisting of a 24aa A-chain and a 29aa B-chain.