The FAC polypeptide binds to the cyclin-dependent kinase, cdc2. Proteins from HSC536N (+FAC) were immunoprecipitated with a preimmune (lane 1) or with anti-FAC affinity purified antibody (lane 2). SDS-PAGE gel was blotted onto nitrocellulose and probed with anti-cdc2 monoclonal antibody or anti-FAC antibody. Molecular weight markers are in kilodaltons.