GDNF and central nervous system cancer: Furthermore, studies of a C6 glioma cell model with curcumin-induced histone hypoacetylation in GDNF promoter II revealed that low acetylation in the Egr-1 binding sites of GDNF promoter II significantly decreased Egr-1 binding to GDNF promoter II, RNA POL II recruitment, and GDNF transcription in C6 glioma cells.