IGF-1 LR3 (Insulin-Like Growth Factor-1 Long Arg3) Information by IGF1LR3 Introduction to the Insulin-Like Growth Factors IGFs are hormones that play prominent roles in cellular communication by allowing cells to interact with their external physiologic environments. The IGF system of communication is frequently referred to as the IGF axis and consists of cell-surface receptors (IGF-1R and IGF2R), ligands (IGF-1 and IGF2 as well as their derivatives) and a family of six ...