We previously published that mice deficient in G protein-coupled receptor kinase 3 (Grk3), an intracellular kinase that negatively regulates GPCRs, have a hypercellular bone marrow comprised of increased Lin- Sca1 + c-Kit + (LSK) HSPCs and selective downstream committed progenitors and an increase of total white blood cells in the peripheral blood (leukocytosis) compared to wildtype (WT) mice [4]. Here, GRK3 is linked to Increased total leukocyte count.