Animal-free Recombinant Human FGF-4 is expressed in human 293 cells as a monomeric glycoprotein with an apparent molecular mass of 17 and 27 kDa. This cytokine is produced in a human cell expression system with serum-free, chemically defined media. Authentic glycosylation contributes to stability in cell growth media and other applications. FGF-4 plays an important physiologically role in the self-renewal of human embryonic stem cells. It also promotes stem cell proliferation. Furthermore, FGF-4 may also aid differentiation which additionally relies on context and concentration.