Homing, adhesion to stroma, cell-cycle status, and apoptosis in Vav-Cre Rb KO primitive hematopoietic cells do not correlate with reduced function. (A) CFCs were transplanted into lethally irradiated animals, and the percentage of CFCs homed to the BM was determined 18 hours after transplantation (n = 4 for both control and Vav-Cre Rb KO). (B) The ability of distinct CAFC populations to adhere to the FBMD-1 stroma cell line after 4 hours was determined using the CAFC adhesion assay as described in “Methods.” There is no difference in the ability to efficiently adhere to stroma cells between control and Vav-Cre Rb KO cells (n = 6 for both control and Vav-Cre Rb KO). (C) BM cells were pulse-labeled with BrdU in vivo, and the frequency of HPCs (L⁻S⁻K⁺ cells) and HSCs (L⁻S⁺K⁺) in the G₀/G₁, S, and G₂/M phases of the cell division cycle were analyzed by flow cytometry (n = 5 for control and n = 7 for Vav-Cre Rb KO). (D) Frequency of HPCs (L⁻S⁻K⁺) and HSCs (L⁻S⁺K⁺) undergoing spontaneous apoptosis in control and Vav-Cre Rb KO animals, determined by staining for annexin V and 7AAD by flow cytometry (n = 3 for both control and Vav-Cre Rb KO). Shown are mean values plus or minus 1 SEM.