FGF1 (Acidic fibroblast growth factor 1) is a member of the fibroblast growth factor family and is involved in embryonic development and organogenesis, morphogenesis, cell growth, tissue repair and tumorigenesis. It regulates endothelial cell migration, proliferation and angiogenesis, and it is involved in learning where it is necessary for memory encoding and enhancement. FGF1 is also an important hormone in metabolic processes including the management of nutrient stress, insulin sensitivity and glycemic control, and it is of interest in injection therapies for type 2 diabetes mellitus. In immunohistochemistry, FGF1 is primarily positive in the cytoplasm of neurons and endothelial cells in the brain, but it also shows positivity in heart muscle, renal tissue, and breast tissue. References: Nat Rev Endocrinol. 2017 Oct;13(10):599-609, PMID: 28664920; Brain Res Bull. 2018 Jul;141:3-12, PMID: 29477835; Neuron. 1991 Sep;7(3):349-64, PMID: 1716928