Fig. 1. Effect of PG-J₂ treatment on the phosphorylation state of ErbB2 and ErbB3. (A) Subconfluent MCF-7 cells were cultivated for 3 or 10 hours in the presence or absence of 10 µM PG-J₂ as indicated. Thereafter the cells were stimulated with NRG1 or NRG2 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) Same experiment as in A; however, the cells were treated with 1 mM ortovanadate prior to PG-J₂ treatment.