CA2 and chronic obstructive pulmonary disease: In addition to these known marker genes, we also observed several previously unreported genes that were upregulated, including S100A7 (S100 Calcium Binding Protein A7), SERPINA6 (Serpin Family A Member 6), and CA2 (Carbonic Anhydrase 2) (Figure 4E), which may serve as potential molecular markers for COPD.