Cited2 deficiency results in loss of HSC quiescence. (A-C) Hoechst 33342 and pyronin Y staining. To analyze the proportion of cells at G₀, mice were killed 4 weeks after pI-pC treatment and BM cells were stained using the DNA dye Hoechst 33342 and the RNA dye pyronin Y in conjunction with cell-surface markers. (A) Representative plots of cell cycle within gated LSKs (top panel) or CD34⁻ LSKs (bottom panel). (B) Summary data of quiescent cells in the LSK population from WT (n = 8) or Cited2^Δ/Δ (n = 7) mice. (C) Summary data of quiescent cells in the CD34⁻ LSK population (n = 4). (D-E) BrdU staining. Wild-type and Cited2^Δ/Δ mice were given BrdU via IP injection and killed 48 hours later for measurement of BrdU incorporation within LSK cells. (D) Representative plots for flow cytometric analysis. (E) Summary data of BrdU⁺ LSK cells (n = 6).