Fig. 7. Effects of NRG1, NRG2 and/or PG-J₂ on apoptosis of MCF-7 cells. Cells were cultured for 72 hours in serum-free medium containing the indicated factors, and apoptotic cells were detected by measuring annexin V-FITC binding by flow cytometry. Inhibitors of MEK1 and -2 (40 µM PD98059) or PI 3-K (4 µM LY294002) were added 1 hour before treatment with the neuregulins. Results are the mean of three determinations from three different experiments. **P0.01; ***P0.001.