Co-immunoprecipitation experiments with lysates from cells harboring chimeric protein (CLL) in the presence and absence of CTCF revealed that RAD21 was pulled down with CLL but not with LCC (Fig. 7f), indicating that it is the N terminal region of CTCF that is involved in mediating the interaction with cohesin. Here, RAD21 is linked to B-cell chronic lymphocytic leukemia.