Human ESC cells were fixed using 1% formaldehyde for 10 min, and followed by 0.125 M glycine 5 min to stop the fixation. Then the cells were harvested, and DNA was fragmented to 300–500 bp by sonication with a microtip attached to Misonix 3000 sonicator. Immunoprecipitation was performed with 3 mg Dynabeads protein G (Life Technology) and AhR antibody overnight at 4C. Afterward, beads were washed, eluted, and reverse cross-linked. DNA was extracted by phenol/chloroform and precipitated. For ChIP-seq, 1 ng precipitated DNA or input was used to generate DNA library by use of Nextera XT DNA sample preparation Kit (Illumina) according to the manufacturer's instruction.