Human/mouse/rat activin A protein is a member of the TGFβ superfamily of growth factors used for maintenance of pluripotency in many induced pluripotent stem cell (iPSC) and embryonic stem cell (ESC) lines, and to induce stem cell differentiation into endoderm and other cell fates. Extensively validated for its reproducibility and as used at the Cambridge Stem Cell Institute. High purity 26 kDa dimer comprising mature domain of activin A protein, animal-free (AF) and carrier-protein free (CF). Rigorously benchmarked against other commercial sources.