IGF-binding proteins prolong the half-life of the IGFs and have been shown to either inhibit or stimulate the growth promoting effects of the IGFs on cell culture. They alter the interaction of IGFs with their cell surface receptors. Interacts with igf2 (By similarity). Interacts with igf1. In early embryos, expressed at a low level in most tissues with expression becoming abundant in the liver by 96 hours post-fertilization (hpf). The expression pattern in adults exhibits sexual dimorphism; in adult males expression is limited exclusively to the liver whereas in adult females expression is observed in the liver and other tissues including the gut, kidney, ovary and muscle. Expressed throughout embryogenesis.