samples were prepared as previously described (Buenrostro et al 2015). 50,000 cells were lysed in 10mM Tris-Cl, 10 mL NaCl, 3mM MgCl2, 0.1% NP-40. Pellets were resuspended in 50 uL Transposition mix (Illumina) and incubated for 30 minutes at 37 C. Samples were purified with MinElute spin columns (Qiagen). Libraries were prepared with Nextera intext adapters and purified with AMPure XP beads (Beckman-Coulter). Sequencing was performed with 2x50 reads on a Illumina HiSeq 2500.