B3 cells containing inducible Ikaros were plated at a density of 0.5 million cells/ml in IMDM medium supplemented with 10% FCS and 1% penicillin/streptomycin. Time point samples were collected by 5 min centrifugation at 1200 rpm. Cell pellets were washed 2 times in PBS, frozen in liquid nitrogen and storaged at -80. Control vector-ERt2 B3 cells were plated at a density of 0.5 million cells/ml in IMDM medium supplemented with 10% FCS and 1% penicillin/streptomycin. Samples were collected by 5 min centrifugation at 1200 rpm. Cell pellets were washed 2 times in PBS, frozen in liquid nitrogen and storaged at -80. DNase-seq libraries were generatedas previously described (Myers protocol: http://myers.hudsonalpha.org/documents/Myers%20Lab%20Sequencing%20Library%20Protocol%20061508.pdf). Libraries were sequenced as 43bp paired-end on the NextSeq 500 Illumina platform. DNase-seq libraries were sequenced to a minimum depth of ~20 million reads per each biological replicate.