Irradiation and 5-FU treatment promote cellular transition of LSK to LSK⁻ cells.

(A) Lethal irradiation causes an increase in the percentage of apoptotic LSK⁻ cells. Mice were treated by two split doses of 550-cGy gamma irradiation (separated by 3 hours), and the apoptotic cells (7AAD⁺Annexin V⁺) in the LSK⁻ population were analyzed by FACS at different time points (n = 4). **: p<0.01. (B) Total number and percentages of LSK and LSK⁻ cells in bone marrow of lethally irradiated WT mice were determined at different time points (n = 4). *: p<0.05; **: p<0.01. (C) Total number and percentages of LSK and LSK⁻ in bone marrow of 5-FU treated WT mice at different time points. The mice were treated with 5-FU (200 mg/kg) by intravenous injection, and the percentages of LSK and LSK⁻ cells were monitored at different time points (n = 4). *: p<0.05; **: p<0.01. (D) The apoptotic rate of LSK⁻ cells in 5-FU treated mice. WT mice were treated with 5-FU, and apoptotic rate of LSK⁻ cells were monitored at different time points (n = 4). *: p<0.05; **: p<0.01.