Smad1/5-deficient BM cells contribute to multilineage long-term reconstitution when transplanted into lethally irradiated recipients. (A) Contribution of donor cells in PB short-term (ST = 4w) and BM long-term (LT = 21w) after transplantation. (B) Distribution of myeloid cells (Mac-1), B cells (B220), and T cells (CD3) within the donor population in PB 21 weeks after transplantation presented as mean ± SD. (C) Number of total cells/femur, primitive LSK cells/femur, and (D) myeloid progenitors in BM 21 weeks after transplantation, as determined by differential counts, FACS, and the number of formed colonies (GM-CFU), respectively (n = 3 donors and 9 recipients). represent WT; and ▬, S1/5^−/−.