Chromatin from 100.000 preGMs or 500.000 GMPs was incubated with antibodies for histone marks (H3K4me3 and H3K27me3) or C/EBPa, respectively. The antibody-bound chromatin was captured with Protein-A sepharose beads, washed, de-cross-linked and precipitated. DNA was extracted using standard phenol-chloroform extraction Precipitated DNA were mixed with 2 ng E. Coli DNA and amplified using NEB Next ChIP-seq sample prep reagent set 1 (New England Biolabs) according to manufacturers protocol.