FGF4

Fibroblast growth factor 4 (FGF4) is a member of the fibroblast growth factor family, a group of secreted signaling proteins involved in development, tissue maintenance, and repair. FGF4 is produced as a small secreted protein that relies on heparan sulfate proteoglycans in the extracellular space to stabilize interactions with cell surface receptors. The protein contains the conserved FGF core domain typical of the family.

FGF4 exerts its effects by binding to fibroblast growth factor receptors (FGFR1–FGFR4) on target cells, often with specific isoforms guiding tissue responses. Receptor activation triggers intracellular signaling cascades such as the MAPK/ERK and PI3K/AKT pathways, and, in some contexts, PLCγ signaling. These signaling events regulate cell proliferation, differentiation, survival, and migration in a context-dependent manner.

Biologically, FGF4 participates in embryonic development and tissue patterning, including roles in limb and neural development and in placental and extraembryonic tissues. In adults, it can contribute to angiogenesis and tissue remodeling during wound healing. Expression of FGF4 is tightly regulated in time and space, consistent with its involvement in developmental processes and organogenesis.

Clinical and research relevance arises from its role in signaling networks that, when dysregulated, can contribute to developmental disorders and cancer. Altered FGF signaling, including changes in FGF4 activity or receptor function, has been observed in various pathologies, making FGFR-targeted therapies and ligand–receptor interaction studies areas of ongoing investigation.