For the ATACseq libraries, induced MEFs were trypsinized, washed, and resuspended in FACS sorting buffer. 12.5k GFP+ cells were sorted per replicate and transpostion reaction. In-house Tn5 transposase was used to insert sequencing adapters and fragmentate cDNA. Greenleaf primer sets (Buenrostro, J., 2015) were used to amplify the fragmented cDNA with 4-6 cycles (KAPA HiFi PCR Kits, catalog number KK2102). AMPure XP beads size selection was performed to recover fragments with length of 200 to 1000 bp.