Identification of INCENP as the Graham Little human autoantigen by western blot analysis. In A: A HeLa cell extract was used by immunoblot against the autoimmune GL serum to show reactivity with a 135 kD polypeptide. Increased amounts of cell extracts are shown in lanes 1–3. In B: a recombinant complex of GST-INCENP (upper arrow), GST-Aurora B (middle arrow) and His-Survivin (lower arrow) shown in lane 1, are blotted against the GL serum (lane 2). Only the INCENP component reacts by blot with the human autoantibody (asterisk in lane 2). The recombinant proteins in lane1, were assayed in a blot control against a specific anti-INCENP serum as shown in lane 3. As marked by asterisk in both lanes 2 and 3, the INCENP component is a major autoantigen recognized by GL human autoimmune serum.