For ATAC-sequencing, 50.000 flow sorted HSPCs, CMPs and GMPs were collected in ice-cold HBSS containing 0.1%BSA and 2mM EDTA, and immediately processed following the protocol of Buenrosto, Greenleaf et al., Curr. Protoc. Mol. Biol., 2015 library preparation has been performed as described in the protocol of Buenrosto, Greenleaf et al., Curr. Protoc. Mol. Biol., 2015