Briefly, cells were cross-linked with 1% formaldehyde for 10 minutes at room temperature. For selected experiments (ChIP for JUN and p-JUN), cells were double crosslinked with 2 mM EGS and 1% formaldehyde for 15 minutes at room temperature. Then it was quenched by 0.125 mol/L glycine for 5 minutes. Followed washing twice by PBS, the cells were resuspended and lysed. Then sonicating with a BioRuptor sonicator was performed. At 4°C, centrifugation at 15,000×g for 25 min was performed. Primary antibodies were added to the chromatin overnight at 4°C. Then 30ul protein A/G magnetic beads for IP were added. After 2-hour incubation at 4°C, the beads were washed three times by washing buffer. ChIP DNA was purified using PCR purification kits after reverse cross-linking at 65°C overnight. Library construction was performed using Trueprep DNA library prep kit V2 for illumina.