{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Napsin A is an aspartic protease enzyme that is primarily expressed in the lung and kidney epithelial cells. Napsin A plays a role in the processing and maturation of surfactant protein B (SP-B) in type II pneumocytes of the lung. SP-B is essential for the surface tension-lowering properties of pulmonary surfactant. Napsin A is highly expressed in lung adenocarcinomas, particularly in tumors of pulmonary origin that exhibit features of alveolar differentiation. High Napsin A expression is also associated with favorable prognosis in lung adenocarcinoma, compared to tumors with low or absent Napsin A expression. Napsin A expression may also have diagnostic implications in certain subtypes of renal cell carcinoma (clear cell RCC) and thyroid tumors (poorly differentiated thyroid carcinomas and anaplastic thyroid carcinomas)."}]}]}