MMP9 and central nervous system cancer: Due to the pivotal role of MMPs in ECM degradation, and consequently to the invasion process, together with the documented association between MMP2 and MMP9 expression and severity of disease in gliomas [20, 21], we interrogated whether the WNK2 methylation status was associated with MMP2 and MMP9 activity levels in a panel of eight glioma cell lines.