BPA Graphic (image) University of California - San Diego Caption Contacts between the ends (red) of estradiol and the estrogen receptor are critical for biological activity. BPA is too short to have both contacts; MBP is longer and can mimic the sex hormone estradiol in the estrogen receptor. Credit UC San Diego School of Medicine Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.