This hybridoma cell line was described as secreting a mouse monoclonal antibody (IgG1) that reacts with rat neonatal fibers and, to a lower extent, with all rat adult type 2 fibers in immunofluorescence; it reacts specifically with neonatal MHCs (myosin heavy chain) in Western blotting; established in 1984 by fusion of NSO myeloma cells with spleen cells from a BALB/c mouse immunized with purified myosin from fetal bovine muscles