Stress hematopoiesis in spleen in Vav-Cre Rb KO animals results in an increased frequency of HSCs and HPCs in cell cycle and reduced function of HPCs. (A) Animals were pulse-labeled with BrdU in vivo, and the frequency of splenic HPCs (L⁻S⁻K⁺ cells) and splenic HSCs (L⁻S⁺K⁺) in the G₀/G₁, S, and G₂/M phases of the cell division cycle analyzed by flow cytometry (n = 9 for both control and Vav-Cre Rb KO). (B) Total number of HPCs (L⁻S⁻K⁺) and HSCs (L⁻S⁺K⁺) in spleens of control and Vav-Cre Rb KO animals (n = 5 for control and n = 7 for Vav-Cre Rb KO). (C) Colony assays were performed to determine the frequency of committed progenitor cells (n = 4 for control and n = 5 for Vav-Cre Rb KO). (D) Number of cells per CFC colony to determine the proliferative potential of the CFCs (n = 4 for control and n = 5 for Vav-Cre Rb KO). (E) Number of colonies per 1 × 10⁴ cells from primary colonies to determine the self-renewal potential of CFCs (n = 4 for control and n = 5 for Vav-Cre Rb KO). Shown are mean values plus or minus 1 SEM; *P < .05.