Insulin-like Growth Factor 2 (IGF-2) is a peptide growth factor involved in regulating embryonic development, tissue growth, and metabolic processes in cynomolgus monkey (Macaca fascicularis), guinea pig (Cavia porcellus), and human (Homo sapiens). The IGF-2 protein is identical at the amino acid level among these species, reflecting strong evolutionary conservation and its essential biological role in mammalian development. IGF-2 is expressed in multiple tissues, particularly during fetal and early postnatal development, where it promotes cell proliferation, differentiation, and survival. IGF-2 primarily binds to the insulin-like growth factor 1 receptor (IGF1R) and can also interact with the insulin receptor, activating intracellular signaling pathways including PI3K–AKT and MAPK that regulate gene expression, cell growth, and metabolism. Additionally, IGF-2 interacts with the IGF-2 receptor (IGF2R), which plays a role in modulating IGF-2 availability and signaling. Across these species, IGF-2 is critical for placental function, fetal growth, and organ development, and it contributes to regulation of muscle growth, tissue maintenance, and metabolic homeostasis. Due to its conserved structure and important physiological roles, IGF-2 is widely studied in developmental biology, endocrinology, and translational biomedical research, particularly in studies of growth regulation, imprinting, and metabolic disease.