Irradiation-enhanced MMP2 promoter activity, mRNA transcription, and protein secretion associated with invasiveness was observed in glioma cells lacking functional PTEN (U87, U251, U373, and C6) but not in those harboring wild-type PTEN (LN18 and LN428) (Park et al., 2006a; Cordes et al., 2003). Here, PTEN is linked to central nervous system cancer.