Figure 1From: Role of activins in embryo implantation and diagnosis of ectopic pregnancy: a reviewStructure of activin mature dimer proteins. The β-subunits are produced as larger precursor proteins, prepro-βA and -βB, that include a signal peptide and pro-region, both of which are cleaved to form the mature β-subunit. Activins are dimers consisting of two β-subunits joined by disulphide bridges.Back to article page