Specificity: Recognizes mitosin, a 350 kD phosphoprotein that is specifically involved in mitotic-phase progression. Mitosin is expressed throughout S, G2, and M phases of the cell cycle, but is absent in G0 and G1. It associates with the mitotic apparatus during M-phase and is redistributed from the nucleus to the centromere, spindle, and midbody during M-phase progression. Its usefulness as a proliferation marker is under active investigation.