Effect of S100A8 deficiency on the cell cycle and function of HSCs under stress. (A) Flow representation of the LSK cell cycle. (B-C) Cell cycle of LSK cells in the S100A8-deficient and control groups after 14 days of 5-FU treatment (B) and IR exposure (C) (n = 4-5). (D) A flow representation of proliferation and apoptosis of LSK cells. (E-F) Proliferation of LSK cells in the S100A8-deficient and control group after 14 days of 5-FU treatment (E) and IR exposure (F) (n = 4–5). (G-H) Apoptosis of LSK cells in the S100A8-deficient and control group after 14 days of 5-FU treatment (G) and IR exposure (H) (n = 4–5). (I-J) The total number of BM colonies in the S100A8-deficient and control groups after 14 days of 5-FU treatment (I) and IR exposure (J) (n = 4). (K) Flow of 5-FU treatment for long-term hematopoietic model development. (L) Dynamic changes in PB WBC in S100A8 deletion and control groups treated with 5-FU (n = 7-8). (M-N) The proportion of PB (M) and BM (N) mature myeloid cells and lymphocytes 16 weeks after the first 5-FU treatment (n = 6–7). (O) Proportion of BM HPCs at 16 weeks after 5-FU treatment (n = 6-7). (P) Proportion of BM HSCs 16 weeks after 5-FU treatment (n = 6-7). ∗P < .05; ∗∗P < .01; ∗∗∗P < .001. BFU-E, burst-forming unit–erythroid; CFU-F, colony-forming unit–fibroblast; CFU-G, colony-forming unit–granulocyte; CFU-GM, colony-forming unit–granulocyte/macrophage; CFU-GEMM, colony-forming unit–granulocyte/erythrocyte/macrophage/megakaryocyte; i.p., intraperitoneal; Rt, routine test; qw, once weekly.