FIG. 8.

NRG1 induces ErbB3 but not ErbB2 down-regulation in MCF7 cells. (A) MCF7 cells were treated without and with 0.1 μM concanamycin (Con), as indicated. Cells were then treated with NRG1 for the indicated times, and lysates were blotted with antibodies to ErbB2 and ErbB3. (B) MCF7 cells were treated with cycloheximide to inhibit protein synthesis and then treated without and with NRG1 for various times. Lysates were blotted with anti-ErbB3 (upper panel), and bands were quantified and plotted (lower panel). ErbB3 half-life was calculated by fitting the data to a single exponential.