GHBPs are soluble proteins containing only the extracellular domain of the flGHR and are able to transport and regulate the bioavailability and half-life of the GH in circulation (Edens and Talamantes,1998). In mammals, when the GH binds to the flGHR monomer, a homodimerization of the receptor is induced, triggering postreceptor signaling events that include recruitment and activation by the phosphorylation of Janus kinase 2 (JAK2).