In the menthol-flavored e-liquid group, genes that are linked with ECM-receptor interactions in small cell lung cancer (COL4A2, LAMB3, LAMA5, and LAMC3) and genes associated with proteoglycans in cancer (CAV1, WNT10B, TFAP4, MMP9, HSPG2, FLNC, ITPR1, CTSL, SMO, ANK1, PLCG2, HBEGF, THBS1, MYC, and PIK3R2) were identified. The gene discussed is MMP9; the disease is small cell lung carcinoma.