Binding of NFY is stabilized by the integrity of the adjacent c-myb binding site. EMSA was performed with the Y+M+ probe (lanes 1 to 3, 7, and 8), Y+M− probe (lanes 4 to 6), and +48/+80 probe (lanes 9 and 10). The reactions contained no protein (lanes 1, 4, 7, and 9) or 20 μg of RPMI-8402 nuclear extract (N.E.). In addition, reactions shown in lanes 3 and 6 contained anti-NFYA antibody (NFYA Ab; from Rockland Immunochemicals). The migration of NFY binding complex (NFY), supershifted complexes (s.s.), or free probe is shown by arrows. Nonspecific complexes are marked by stars.