AP-2α isoforms 1a, 1b, and 1c are expressed in breast cell lines and tissues. (a) cDNA was generated from the indicated breast cell lines (left) and normal breast samples (right) and the relative amount of the different AP-2α isoforms was determined by real-time PCR as described in the Materials and methods. (b) HepG2 cells were transfected with pcDNA3 expression vectors encoding each isoform and harvested after 48 h. Two different amounts of cell lysate (5 and 2.5 μg) were loaded for each isoform. Western blot analysis was performed with a pan-AP-2α antibody, 3B5, which recognises an epitope in the DNA-binding domain of the protein common to all isoforms. (c) Protein lysates (30 μg) derived from the indicated cell lines were analysed by western blot with isoform-specific antibodies. As a loading control, two amounts of lysate from HepG2 cells overexpressing each isoform from (b) were loaded on each gel and the blots were also reprobed for actin (lower panels).