IGF-binding proteins prolong the half-life of IGFs and have been shown to either inhibit or stimulate the growth promoting effects of the IGFs in cell culture. They alter the interaction of IGFs with their cell surface receptors (By similarity). May be a putative tumor suppressor protein. . This is the function of IGFBPL1 (insulin like growth factor binding protein like 1, Ensembl gene identifier ENSG00000137142).