Refer to protocol documents for differing sources, UW: DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen) ACC-207 http://www.dsmz.de/ or Yale (Stanford): National Cell Culture Center http://www.nccc.com/
CTCF zinc finger transcription factor. A sequence specific DNA binding protein that functions as an insulator, blocking enhancer activity. It has also been suggested to block the spreading of chromatin structure in certain instances.