Anti-fibrosin antibodies are used in the immunodetection of the protein encoded by the FBRS gene. In humans, the canonical protein has a reported length of 460 amino acid residues and a mass of 48.4 kDa. Alternative splicing is reported to yield 2 different isoforms for this protein. Other names for this target antigen include fibrogenic lymphokine, fibrosin 1, probable fibrosin-1 long transcript protein, and probable fibrosin-1.