54,000 AVM cells cultured in NG and HG for 48hrs were used for ATAC-sequencing. Similar to Buenrostro et al. (Nat Methods. 2013 Dec;10(12):1213-8), unfixed AVM cells were lysed and immediately transposed using Nextera DNA library preparation kit (FC-121-1030, Illumina) followed by column purification with MinElute Reaction cleanup kit (Qiagen). ATAC-seq libraries were generated from transposed and amplified DNA using Nextera index primers. The quality of the libraries was assessed using Agilent Bioanalyzer High Sensitivity DNA analysis kit and sent for 50bp paired-end sequencing on Illumina HiSeq 2000 platform to Epigentek Group Inc. (Farmingdale, NY).