library_construction_protocol: The bound and unbound fractions of each sample were cut separately as thin gel slice, extracted by acrylamide gel extraction buffer (soaking a 55C for more than 30mins). Each fraction of DNA pool was purified and further amplified by uniquely indexed Illumina primers set for at least 12 cycles (annealing temperature 52C, extension time 30s). All samples were pooled together for Illumina Novaseq. Synthetic DNA library was prepared by ordering 20 degenrate ologos containing triply randomized sites within the putative ZNF626 binding site (54bp long). Reversed PE2 primer was used to anneal and extend the ssDNA library to make dsDNA library.