Fig. 5.

ErbB4 transactivation by TNF protects colonic epithelial cells from cytokine-induced apoptosis. YAMC cells expressing either vector (YAMC-vector) or ErbB4 (YAMC-ErbB4) were incubated with 10 μM TAPI-1 for 30 min (A) or ErbB4 blocking antibody for 1 h (B) before treatment with 1 μg/ml cycloheximide (CHX) and 100 ng/ml TNF for 3 h. Caspase-3 activation and poly(ADP-ribose) polymerase (PARP) cleavage were assessed by Western blot analysis of whole cell lysates. Actin was used as a loading control. C: vector and ErbB4-expressing YAMC cells were incubated with 10 μM TAPI-1 for 30 min or with an ErbB4 blocking antibody for 1 h before treatment with 1 μg/ml cycloheximide and 100 ng/ml TNF for 5 h. Subsequently, cells were subjected to terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling kit (TUNEL) apoptosis assay. Labeled nuclei from at least 5 random fields per condition were counted in each of 3 experiments.