Competitive RAI3 Immunohistochemistry on cancerous breast tissue. Immunohistochemical staining of cancerous breast tissue (A, B) in comparison to a competitive immunohistochemical approach (C, D). Strong staining of tumourous tissue was observed using a 1:50 dilution of anti-RAI3 Mab 24 2.3 (A, B). Staining is inhibited by pre-incubation of the antibody with 200-fold molar excess of recombinant RAI3 protein (C, D). Magnifications: A, C: 200×; B, D: 400×.