Serum carbohydrate antigen-6 (Krebs von den Lungen-6 or KL-6), lactate hydrogenase (LDH), and surfactant proteins A and D (SP-A and SP-D) levels have been evaluated as biomarkers of IPF; each possesses some predictive ability, but none is perfect [2, 5–8]. The gene discussed is MUC1; the disease is idiopathic pulmonary fibrosis.