Figure 5.

Recombinant rat epiregulin stimulates EGF receptor activation in cultured RASM cells. Serum-starved RASM cells were either untreated (Control) or stimulated for 5 min with PDGF-BB (50 ng/ml), EGF (100 ng/ml), betacellulin (100 ng/ml), or 2× concentrated conditioned media (CM) obtained from epiregulin or mock-transfected COS-7 cells as indicated. Cell lysates were immunoprecipitated with anti-P-Tyr antibodies, and recovered proteins were resolved by SDS/PAGE. Duplicate gels were immunoblotted with either anti-P-Tyr (A) or anti-EGF receptor (B) antibodies. Anti-P-Tyr-recovered EGF receptors are indicated by the arrow (B). Data are representative of independent experiments performed on two separate occasions.