Inhibition of cell cycling with palbociclib equalizes the function of WT and Cd53^−/− HSCs. WT and Cd53^−/− mice were treated with palbociclib or vehicle control, daily via oral gavage, beginning 1 day before 7 days of G-CSF treatment, and 50 sorted HSCs were competitively transplanted against 2.5 × 10⁵ WBM into lethally irradiated recipients. (A) Engraftment of vehicle controls (no palbociclib), including total leukocyte chimerism (left) and individual lineages at 24 weeks post-transplant (right). n = 5 recipients per group in 2 independent experiments. (B) Engraftment of palbociclib treated groups, including total leukocyte chimerism (left) and individual lineages at 24 weeks post-transplant (right). n = 5 to 6 recipients per group in 2 independent experiments. (C) Volcano plot of DEGs (P_adj < .05) comparing mobilized splenic HSCs from WT and Cd53^−/− mice treated with G-CSF and palbociclib. Error bars represent mean ± SEM. ∗P < .05; and ∗∗P < .01 by an unpaired Student t test.