Serpin A1a, also known as alpha-1-antitrypsin, belongs to the serpin superfamily of proteinase inhibitors. It is one of five alpha 1-proteinase inhibitors produced in mice. Serpin A1a is produced in the liver, then secreted into the bloodstream. It inhibits a number of serine proteases, including elastase, trypsin, plasmin, and thrombin (1, 2). Serpin A1a’s major function is to protect the lungs from neutrophil elastase. Serpin A1a deficiency can cause complications such as emphysema, and chronic obstructive pulmonary disease (COPD).