Fig. 8. Effect of PG-J₂ on T47D and SKBR3 breast cancer cell lines. (A) Effect of PG-J₂ treatment on the phosphorylation state of ErbB2 and ErbB3. Subconfluent cells were cultivated for 10 hours in the presence or absence of 10 µM PG-J₂ as indicated. Thereafter the cells were stimulated with NRG1 for 5 minutes and the lysates were used for immunoprecipitation (IP) with anti-ErbB2 or anti-ErbB3 polyclonal antibodies. The immunoprecipitates were subjected to SDS-polyacrylamide gel electrophoresis and immunoblotted with the indicated antibodies. (B) Effects of NRG1 and PG-J₂ treatment on cell proliferation. Both cell lines were treated with 30 nM of NRG1 in the presence or absence of PG-J₂, and the incorporation of [³H]thymidine into DNA was determined. Results are the mean of three determinations from two different experiments. **P0.01; ***P0.001.