We then incubated COPD sputum from the start of an exacerbation at dilutions of 1:60 and 1:80 with synthetic proteases, NE 0.02 mg/mL, and cathepsin G 100μU/μL and incubated at 37 °C for 6 h. The gene discussed is CTSG; the disease is chronic obstructive pulmonary disease.