S2 cell fixation and following ChIP were performed with ChIP-IT high sensitivity kit (#53040, Active motif) following the manufacturer’s instruction. Sonication of S2 cells were done with Bioruptor sonicator (UCD-200, diagenode) using following setting 0.5min on, 1min off for total 15min. Fragment size were around 500-600bp. ChIP grade GFP antibody (Abcam, ab290) were used to pulled down sheared chromatin. Libraries were generated using reagents provided in the Illumina TruSeq ChIP Sample Preparation Kit (IP-202-1012).