Behavior of CD166^−/− HSPC under hematopoietic stress. (A) Survival of WT and KO mice after a single intraperitoneal injection of 5-FU (150 mg/kg, arrowhead) (n = 14 per genotype). Survival was monitored daily. *P < .05; Kaplan-Meyer curves were analyzed with a log-rank (Mantel-Cox) nonparametric test. (B) Total white blood cell count per femur before (day 0) and on days 5, 10, 17, and 24 after treatment with 5-FU (n = 4 per genotype per time point). *P < .05 compared with WT. (C) Phenotypic analysis of HSPC from BM of WT and KO mice 5, 10, 17, and 24 days post 5-FU (n = 4 per genotype per time point). *P < .05 compared with WT. (D) Representative analysis of LSK cells from 1 mouse per genotype per time point with Hoechst 33342 and Pyronin Y (n = 4 per genotype per time point). (E) Percentage of LSK cells in the G0 phase of cell cycle on days 5, 10, 17, and 24 post-5-FU treatment analyzed as shown in (D) (n = 4 per genotype per time point). *P < .05 compared with WT. (F) Expression of CD166 on BM-derived LSK cells from 1 representative control mouse or from each of 3 separate mice irradiated with 400 cGy or treated with 150 mg/kg 5-FU 10 days earlier.