FGF4, or Fibroblast Growth Factor 4, is a protein that plays a crucial role in various biological processes, including cell growth, development, and tissue repair. It is part of the fibroblast growth factor family, which consists of several proteins that interact with specific receptors on cell surfaces to trigger signaling pathways. This protein is particularly important during embryonic development, influencing the formation of limbs and other structures. Additionally, FGF4 has been studied for its potential therapeutic applications in regenerative medicine and cancer treatment, as it can promote cell proliferation and survival in certain contexts.