 This oxygen tension upregulates HIF1A, which shifts energy production to glycolysis, allowing for the cell to survive in oxygen-poor surroundings.Indeed, deletion of HIF1A increases HSC proliferation and eventually depletes the LT-HSC storage pool.This suggests that the hypoxic environment of the bone marrow, partially determined by the distance from the sinusoids of the perivascular niche, maintains the quiescent state of LT-HSCs in an effort to retain stem cells with differentiation potential.