design: MC and NC were harvested and fixed according to the Diagenode s. a. (Belgium) company guidelines. Briefly, the tissues were rinsed in ddH2O, dried with paper towels, and placed in a crosslinking bag, which was then put in a 50ml falcon tube with the crosslinking buffer (10x phosphate buffered saline (PBS), 37% pofmaldehyde, ddH2O) containing 1% formaldehyde. Crosslinking took place in a vacuum desiccator (~ - 950 Millibars) for 15 minutes. 2,5 ml of the solution was replaced by 2,5ml of 1.25 M glycine in ddH2O, and placed in the vacuum for additional five minutes. Crosslinking solution was removed, and samples were washed three times in ddH2O. Tissues were removed from the bags, dried with paper towels and placed into new 50 ml falcon tubes. Tubes were snap-frozen and stored in -80C till further processing. Chromatin immunoprecipitation was performed at Diagenode s. a. according to the companys guidelines with H3K4me3 antibody.