SULFATE 2 (IMAGE) Rice University Caption Rice University scientists developed cells engineered to express therapeutic proteins, specifically a thrombin inhibitor. The key is the site-specific insertion of sulfotyrosine (sTyr), a mutant of the standard amino acid tyrosine found naturally only in the crested ibis. Credit Xiao Lab/Rice University Usage Restrictions NONE License Original content 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.