has role hormone molecule insulin family Insulin superfamily genes are ubiquitous in vertebrates, and have been identified in invertebrates, including insects, molluscs, and the nematode Caenorhabditis elegans. Seven members of the insulin superfamily have been identified in humans, including insulin, insulin-like growth factors (IGFs) I and II, relaxins HI and HII, early placenta insulin-like peptide (EPIL), and relaxin-like factor.