Description: Napsin is found in two isoforms, A and B, with highly homologous gene sequences. Napsin A has a molecular weight of 35 kDa and is also known as TA02. It is an aspartic proteinase expressed in the lung and involved in processing surfactant protein B. It is also expressed in the kidney. This antibody may be useful as a tumor marker for primary lung adenocarcinoma. Napsin expression correlates with the differentiation grade of lung adenocarcinoma.