Cortex of human embryonic kidneys were micro-dissected and fixed in crosslinking buffer containing 1% PFA for 30 min, then homogenized, followed by chromatin extraction and sonication. Sonicated chromatin was then immuno-precipitated with the indicated antibodies. The precipitated DNA was subsequently collected with Qiagen PCR product purification kit. Mouse embryonic kidneys were processed in a similar way. Libraries were constructed using ThruPLEX-FD Prep Kit (Rubicon Genomics), and subsequently sequenced by Illumina HiSeq 2000.