After 16hrs of treatment, cells were washed once in PBS, and fixed with 1%formaldehyde for 10 minutes at room temperature. After quenching and nucleus extraction, chromatin was released by nuclear lysis and sonicated using Bioruptor Pico sonicator for 10 cycles (30sec on/30sec off). Protein/DNA complex was immunoprecipitated using 0.2µg PU.1 antibody or equivalent amount of Rabbit IgG, and ChIP DNA was released by reverse crosslinking at 67ºC overnight, followed by column-based DNA purification. ChIP-seq library preparation was performed by BGI Genomics using the following steps: ChIP DNA was end repaired for 3'-dA overhang and adapters ligated. PCR amplification was then performed, amplified library DNA purified, and subjected to sequencing on DNBSEQ platform for 20 million reads per sample using single-end 50bp strategy.