FLT3 receptor is dispensable for steady- state maintenance of adult HSCs. (A) Representative FACS plots of LSK and LSKCD150⁺ cells in BM of 9- to 18-week-old WT and Flk2^−/− mice. Numbers indicate frequencies of populations within indicated gates or quadrants of total BM cells. Cells have first been gated as Lin⁻ as indicated. In the right panels, only gated c-KIT⁺ cells are displayed. (B) Mean (SEM) numbers of LSKCD150⁺ cells in BM (per 2 tibiae and 2 femora) of 9- to 18-week-old WT and Flk2^−/− mice (n = 8-10 per genotype), from at least 2 different litters. ns indicates not significant.