It has been shown that occludin is downregulated and subsequently phosphorylated in human high-grade gliomas, thus causing increased permeability of the TJs as a result of the altered interaction between phosphorylated occludin and ZO1, ZO2 and ZO3 (Rubin and Staddon, 1999; Papadopoulos et al., 2001; Kale et al., 2003). Here, OCLN is linked to central nervous system cancer.