Increased engraftment by in vivo PGE₂-treated BMMCs is a transient phenomenon. (A) Serial competitive transplantation scheme. Donor mice (CD45.1) are treated with PGE₂ or vehicle, and BMMCs are harvested after treatment. A mixture of CD45.1-expressing donor cells and CD45.2-expressing untreated competitor cells are transplanted into lethally irradiated CD45.2 primary recipient mice. After 36 weeks, BMMCs are harvested from the primary recipient mice and used as donor cells for a second round of competitive transplantation. (B) The percentage of donor-derived (CD45.1) LSK cells in the primary recipient bone marrow 36 weeks after transplantation. (C) Percentage of donor-derived (CD45.1) myeloid cells, T cells, and B cells in the peripheral blood of secondary recipients 10 weeks after transplantation.