Nras is dispensable for normal function of HSCs. (A) Total number of CD150⁺CD48⁻LSK HSCs, CD150⁻CD48⁻LSK MPPs, and LSK cells in BM and spleens (SP) of WT (Nras^+/+) and Mx1-cre; Nras^fl/fl (Nras^Δ/Δ) mice 2 weeks after pIpC treatment (n = 10). (B) BrdU incorporation in WT and Nras^Δ/Δ HSCs after 24-hour BrdU incorporation (n = 6). SLAM, signaling lymphocyte activation molecule. (C) BM and spleen cellularity in WT and Nras^Δ/Δ mice (n = 10). (D) 5 × 10⁵ donor BM cells from Mx1-cre; Nras^fl/fl (Nras^Δ/Δ) or littermate control mice at 2 weeks after pIpC treatment were transplanted into irradiated recipient mice with 5 × 10⁵ recipient BM cells. Donor cell reconstitution in the myeloid (Gr-1⁺ or Mac-1⁺ cells), B- (B220⁺), and T- (CD3⁺) cell lineages was monitored for 4 to 20 weeks after transplantation (n = 5 recipients/genotype). Only the week 4 time point is significant for B- (P < .001) and T-cell (P = .024) repopulation. (E) Competitive repopulation of Mx1-cre; Nras^G12D/fl; (Nras^G12D/Δ), Mx1-cre; Nras^G12D/+ (Nras^G12D/+), or littermate control BM cells (n = 5 recipients/genotype). Two-tailed Student t tests were used to assess statistical significance and P < .001 between Nras^G12D/+ or Nras^G12D/Δ and control at 8, 12, 16, and 20 weeks with no significant difference between Nras^G12D/+ and Nras^G12D/Δ.