Fig. 2. Effect of PG-J₂ treatment on the phosphorylation state of EGF-R and IGF-IR. Subconfluent MCF-7 cells were cultivated for 10 hours in the presence or absence of 10 µM PG-J₂ as indicated. Thereafter the cells were stimulated with EGF or IGF-I for 5 minutes and the lysates were used for immunoprecipitation (IP) with anti-EGF-R or anti-IGF-IR polyclonal antibodies. The immunoprecipitates were subjected to SDS-polyacrylamide gel electrophoresis and immunoblotted with the indicated antibodies.