It is conceivable, that in gliomas high levels of HDAC4 expression in complex with MEF2 acts as transcriptional repressor of KLF4 and, consequently, of zonula occluden-1, claudin-5, and occludin gene expression, which may be another important component in the mechanism of BBB disruption in gliomas. The gene discussed is OCLN; the disease is central nervous system cancer.