MMPs play a critical role in tumor invasion and metastasis by degrading the molecules constituting the extracellular matrix (ECM).19, 41, 42 Of the more than 20 known human MMPs, MMP2 and MMP9 seem to play crucial roles in tumor invasion and metastasis due to their ability to degrade the ECM, observed in a variety of cancer cell lines.43, 44 Here, we detected the effects of nevirapine on MMP‐2 and MMP‐9 expression in WRO 82‐1 cells and tumor xenografts. This evidence concerns the gene MMP9 and cancer.