MMP9 and chronic obstructive pulmonary disease: Disease-target-compound network and PPI network analysis showed that EGFR, MMP9, PTGS2, MMP2, APP, and ERBB2 may be the core targets of SZYQD in the treatment of COPD, which were mainly involved in cancer in the pathway, calcium signaling pathway, PI3K-Akt signaling pathway, and Ras signaling pathway.