MMP9 and chronic obstructive pulmonary disease: Five genes were identified with higher values of ‘Degree’ (above twofold of the median value), ‘Betweenness centrality’ and ‘Closeness centrality’ (above the median value) as the key targets of chenpi preventing COPD and its progression to lung cancer, they were AKT1, IL6, VEGFA, MMP9 and TP53 (Table 2).