Stickleback Basic Fibroblast Growth Factor (FGF2, also known as bFGF) is a heparin-binding growth factor belonging to the fibroblast growth factor (FGF) family, a group of signaling proteins that regulate cell proliferation, differentiation, angiogenesis, and tissue development across vertebrates. In the three-spined stickleback (Gasterosteus aculeatus), FGF2 is expressed in developing tissues, epithelial cells, fibroblasts, and endothelial cells, where it contributes to embryonic development, tissue growth, and regeneration. FGF2 signals through fibroblast growth factor receptors (FGFRs) in the presence of heparan sulfate proteoglycans, activating conserved intracellular pathways such as MAPK/ERK and PI3K–AKT, which promote cell proliferation, migration, and vascular development. In stickleback biology, FGF2 is particularly important during embryogenesis and skeletal development, processes that are well studied in this species due to its usefulness as a model organism for evolutionary and developmental biology. Sticklebacks are widely used to study vertebrate morphological evolution and skeletal patterning, and investigation of FGF signaling pathways, including FGF2, helps researchers understand how growth factor networks regulate tissue development and evolutionary changes in vertebrate body structures.