Figure 4. Exo1^mut mice become IR sensitive after 5-FU induced HSC cell cycle entry.

(A) Age matched WT and Exo1^mut mice were treated with 150 mg/kg 5-FU followed by 4Gy IR 5 days post 5-FU. Seven days post dual treatment 3 mice from each group were sacrificed and bone marrow cellularity and CFU counts were measured. Error bars represent SEM. (B) WT and Exo1^mut mice were treated with the combination of 5-FU and IR and 14 days post treatment 3 mice were sacrificed and flow cytometry was performed on whole bone marrow to determine SKL numbers. Error bars represent SEM. (C) Dual treated WT and Exo1^mut whole marrow were mixed 1:1 and injected into lethally irradiated recipients. Animal chimerism was measured using CD45.1/2 flow cytometry 8 weeks post transplant. (D) Numbers of WT and Exo1^mut mice that survived the 5-FU + IR combination treatment two months post treatment. P values were calculated by 2-tailed student t test. * p<0.05 vs. WT.