Insulin-like Growth Factor 2 (IGF-2) is a peptide growth factor involved in regulating embryonic development, tissue growth, and metabolic processes in swine (Sus scrofa), rabbit (Oryctolagus cuniculus), dolphin (family Delphinidae), and bat (order Chiroptera). The IGF-2 protein is identical at the amino acid level among these species, reflecting strong evolutionary conservation and its essential 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. In addition, IGF-2 interacts with the IGF-2 receptor (IGF2R), which regulates IGF-2 availability and signaling through ligand internalization and degradation. Across these species, IGF-2 is critical for placental function, fetal growth, and organ development, and it contributes to regulation of muscle development, tissue maintenance, and metabolic homeostasis. Due to its conserved structure and key developmental roles, IGF-2 is widely studied in mammalian physiology, developmental biology, and comparative biomedical research.