Anti-OCC-1 antibodies enable researchers to detect and measure the OCC-1 antigen in biological samples. This target is a reported synonym of the FSTL1 gene, which encodes follistatin like 1. This protein is known to function in the differentiation of certain cell types, among other biological roles. The human version of OCC-1 has a canonical amino acid length of 308 residues and a protein mass of 35 kilodaltons, although 2 isoforms have been identified. It is reported to be a secreted protein.