MMP9 and cancer: We also found that a specific module consisted of 19 key genes, namely, AURKA, KIF11, TK1, CDK1, CCNA1, AURKB, CCNA2, PLAU, SERPINA1, STSB, CTSS, REN, SELP, PPARG, LGALS3, MMP1, MMP9, NOS2, and LCN2. The functional analysis further indicated that these 19 genes were indeed involved in pathways in cancer.