Fig. 1.

TNF transactivates ErbB4 in colonic epithelial cells. A: ErbB4 expression in young adult mouse colon (YAMC) cells stably overexpressing ErbB4 (YAMC-ErbB4) or vector (YAMC-vector) was assessed by Western blot with antibodies specific for ErbB4 or actin (loading control). B: YAMC-ErbB4 cells were treated with TNF for 30 min at the indicated concentrations or with 10 ng/ml heregulin (HRG) for 10 min. C: YAMC-ErbB4 cells were treated with TNF (100 ng/ml) for the indicated time points or with HRG (10 ng/ml) for 10 min, as a positive control for activation. D: Immorto-Min colon epithelial (IMCE) cells were treated with 100 ng/ml TNF for the indicated times or with 10 ng/ml HRG for 10 min. E: Madin-Darby canine kidney (MDCK) cells were treated with TNF (100 ng/ml) for the indicated time points or with HRG (10 ng/ml) for 10 min. Cell lysates were analyzed by Western blot with antibodies specific for phosphorylated (PY-1284) ErbB4, total ErbB4, or actin (loading control). All blots are representative of at least 3 experiments.