CTCF expression patterns in pediatric ALL samples and leukemic cell lines. (A) Western blot analysis of unpaired samples from 8 patients (n = 8, 4 ND and 4 CR). CTCF was over-expressed in the ND samples and displayed reduced expression after CR. A sample from one pediatric patient with immune thrombocytopenic purpura (ITP) was used as a negative control, and GAPDH was used as a loading control. (B) Western blot analysis of paired samples taken from 16 pediatric ALL patients (n = 32). The results from 3 patients are shown, including 1 patient with a t(1;19) (E2A-PBX1) translocation, 1 with a t(12;21) (TEL-AML1) translocation, and 1 without any translocations. CTCF was over-expressed in the ND samples and displayed reduced expression after CR. (C) The expression of CTCF rebounded after relapse and maintained normal levels in the CR phase. A total of four relapsed cases were assessed, and the results from two cases are presented. (D) The mRNA and protein levels of CTCF in various lymphoblastic leukemia cell types were evaluated by real-time PCR and Western blot. The relative mRNA expression levels were analyzed and presented as mean ± SD from triple replications (p = 0.831). Nalm-6 is a pre-B ALL cell line with no fusion gene. Reh is a pre-B ALL cell line with the TEL-AML1 fusion gene. Jurkat is T lymphocyte cell line. GAPDH was measured as the loading control.