Animal-free Recombinant Human TGF beta 1 is expressed from human 293 cells as a mature disulfide-linked homodimer with an apparent molecular mass of 25 kDa. Tests indicate that TGF beta 1 is as efficient at inducing IL-17 expression in Th17 cells, as cytokine purified from human platelets. This product is produced in a human cell expression system with serum-free, chemically defined media.