AAV2 induction of apoptosis/cell death in the different breast cancer lines correlates with Rep protein expression. For detecting Rep proteins in Western blots, total protein extracts were prepared as we have previously described [13, 48]. Sixty micrograms of total protein extracts from AAV2 infected and control (A) MCF-7, (B) MDA-MB-468, (C) MDA-MB-231 and (D) nHMECs monolayer cultures were resolved in a 7.5% SDS-polyacrylamide gel electrophoresis gel and detected with an AAV2 Rep-specific antibody (Progen). Results shown are representative of three individual experiments. t, time; +, AAV2 infected; -, control. Double asterisks (**) indicate dimer form of protein, single asterisk (*) indicates the monomer form.