Both Smad1- and Smad1/5-deficient BM cells display normal self-renewal and differentiation capacity after competitive BM transplantation. (A) Short-term contribution (ST) in PB and long-term (LT) reconstitution in BM in primary and (C) secondary recipients after competitive transplantation, as measured by Ly5.2/Ly5.1 contribution. (B) Distribution of myeloid cells (Mac-1), B cells (B220), and T cells (CD3) within the donor population in PB from primary and (D) secondary recipients analyzed by FACS long-term after transplantation. Data are mean ± SD (n = 9/5/8 donors and n = 25/15/19 recipients for WT, S1^−/−, and S1/5^−/−, respectively, for primary transplantations, and n = 7/5/3 donors and n = 21/15/9 recipients for WT, S1^−/−, and S1/5^−/−, respectively, for secondary transplantations). represent WT; , S1^−/−; and ▬, S1/5^−/−. (E) Representative PCR screen of individual hematopoietic colonies from WT and S1/5-deficient mice to determine deletion (total number of colonies screened, n > 240). Lanes 1 to 4 indicate floxed (no band) and deleted (300 bp) Smad1 in WT (lanes 1 and 2) and S1/5^−/− colonies (lanes 3 and 4); lanes 5 to 8, floxed (2.3 kb) and deleted (387 bp) Smad5 in WT (lanes 5 and 6) and S1/5^−/− colonies (lanes 7 and 8).