CTCF is a transcription factor and a candidate tumor suppressor that contains a 
DNA-binding domain composed of 11 zinc fingers. We reported previously that CTCF 
is differentially regulated during differentiation of human myeloid leukemia 
cells. In this study we aimed to investigate the role of CTCF in myeloid cell 
differentiation. A human cell line, K562, that can be chemically induced to 
differentiate into various hematopoietic lineages was chosen as a model system 
for this study. Several K562 cell lines with constitutive and conditional 
expression of CTCF have been generated. By using these model systems we 
demonstrated that: (i) ectopic expression of CTCF in K562 cells led to growth 
retardation and promotion of differentiation into the erythroid lineage; (ii) 
CTCF knock-down significantly inhibited differentiation of K562 cells into 
erythroid lineage; (iii) differentiation of K562 into the megakaryocytic lineage 
was not significantly affected; and (iv) down-regulation of MYC has been 
identified as one of the mechanisms by which CTCF promotes erythroid 
differentiation. Taken together our results demonstrate that CTCF is involved in 
the control of myeloid cell growth and differentiation.