Figure 4.

Effect of Reg IV on epidermal growth factor receptor (EGFR) phosphorylation. (a) 10 µL of Reg IV‐conditioned medium and control medium were analyzed by Western blot with a rabbit polyclonal antibody against Reg IV. (b) LNCaP cells were cultured with either EGF (100 nM) or transforming growth factor (TGF)‐α (10 nM) for 3 min. Whole‐cell lysates were prepared and analyzed by Western blot with antiphospho‐EGFR (Tyr¹⁰⁶⁸) antibody. (c) LNCaP cells were cultured with either Reg IV‐CM or control medium for 3 min. Whole‐cell lysates were prepared and analyzed by Western blot with antiphospho‐EGFR (Tyr⁹⁹²) or antiphospho‐EGFR (Tyr¹⁰⁶⁸) antibody. The samples were also probed with anti‐EGFR antibody to verify equal loading. (d) LNCaP cells were cultured with either EGF (100 nM) or TGF‐α (10 nM) for 1, 2 or 3 days. Whole‐cell lysates and culture medium were analyzed by Western blot with anti‐Reg IV antibody. (e) Expression of Reg IV and EGFR was examined by immunohistochemistry in serial sections of prostate cancer. Inset, phospho‐EGFR (Tyr¹⁰⁶⁸) staining of a serial section. Scale line, 25 µm. (f) Expression of TGF‐α was examined by immunohistochemistry. Scale line, 25 µm.