CCCTC-binding factor (CTCF) is a ubiquitous Zn-finger-containing protein with 
numerous recognized functions, including, but not limited to, gene activation 
and repression, enhancer-blocking, X-chromosome inactivation, and gene 
imprinting. It is believed that the protein performs such a variety of functions 
by interacting with an array of very diverse proteins. In addition, CTCF 
undergoes several post-translational modifications, including 
poly(ADP-ribosyl)ation. The PARylated form of CTCF has recently been implicated 
in two important functions: gene imprinting and control of ribosomal gene 
transcription. Here, we summarize and critically discuss the available data on 
the interplay between CTCF and poly(ADP-ribosyl)ation in these two processes. We 
consider the newly described phenomena in the broader context of PARP's 
activities, including the crucial role of protein PARylation in the regulation 
of the genome methylation pattern.