MMP9 and cancer: In order to provide a solid practical and theoretical basis for the subsequent research of targeted inhibitors, the expression levels of MMP9 in different cancers from GEPIA2 database were observed and analyzed to gain a comprehensive understanding in expression pattern, including SARC (sarcoma), GBM (glioblastoma multiforme), KIRC (kidney renal clear cell carcinoma), LUSC (lung squamous cell carcinoma), COAD (colon adenocarcinoma) and BLCA (bladder urothelial carcinoma).