To determine whether the observed hypoxia-induced leukocytosis represents increased production of mature leukocytes, we assessed the number and proliferation of bone marrow HSPC, which consist of hematopoietic stem cells (HSC), lineage- Sca-1+ c-Kit+ (LSK or HSPC) cells and granulocyte macrophage progenitors (GMP) (Supplementary Figure 3A). Here, KIT is linked to Increased total leukocyte count.