FIGURE 3.

PI3K activity and p85-ErbB3 interaction in LNCaP cells are independent of EGFR/ErbB2 activity. Serum-starved LNCaP cells (2 days) on 10-cm plates were treated with EGFR/ErbB-2 dual inhibitor lapatinib (10 μm) or vehicle (DMSO; D) for 6 h. A, cell lysates were immunoprecipitated (IP) with anti-Tyr(P), followed by immunoblotting for EGFR, ErbB2, or ErbB3. Whole cell lysates prior to immunoprecipitation were also immunoblotted as indicated for input EGFR, ErbB2, ErbB3, and Akt and for pAkt. B and C, cell lysates were immunoprecipitated with anti-p85 or rabbit IgG (Ig), followed by immunoblotting for ErbB3 (B) or Tyr(P) (C).