Primary myoblast samples were collected in growth medium at low density, and both primary myotubes and RD cells were collected after being cultured in differentiation medium (72 h for myotubes, 24 h for RD cells). Libraries were generated from immunoprecipitated DNA as outlined in the Illumina DNA Library Construction Kit protocol except that 21 rounds of PCR were performed for amplification, and DNA fragments ranging from 200-350 bp were isolated during size selection on agarose gel.