SFTPA2 and lung adenocarcinoma: Similarly, this DCB subtype specificity also extends to lung cancer: 4 of the 6 lung DCB genes (CXCL17, SFTA3, SFTPA2, and SLC34A2) were upregulated in the plasma of patients with lung adenocarcinoma compared to those with squamous cell carcinoma (Fig. 4d).