Effect of estrogen on ErbB4 shedding.

<p>(A) Western analysis of MCF-7 cells treated with or without 10 nM estradiol or 100 ng/mL PMA for 24 hours. The amount of shed ErbB4 ectodomain (100 kD) was detected with mAb 1479 under non-reducing conditions from culture medium and full-length ErbB4 (180 kD) with anti-ErbB4 (E-200) from cell lysates. Anti-actin was used as a loading control. The experiment was repeated four times with similar results. (B) TACE activity assay of MCF-7 cells treated for 30 min with or without 10 nM estradiol or 100 ng/mL PMA. After the treatments, TACE substrate peptide that becomes fluorescent upon cleavage was applied to the cells at time point 0. *, <i>P</i><0.05 compared to control at the time point.