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Activin A is a dimeric glycoprotein belonging to the transforming growth factor-beta （TGF-β） superfamily of cytokines. It is involved in various biological processes, including embryonic development, reproductive function, and regulation of the immune system. Activin A is produced by a wide range of cell types, including immune cells, endothelial cells, and reproductive tissues. It exerts its effects by binding to the activin type II receptors, leading to the activation of downstream signaling pathways involved in cell proliferation, differentiation, and immune modulation. Activin A has been implicated in the regulation of inflammation, tissue repair, and the pathogenesis of various diseases, including cancer and autoimmune disorders.