Systemic PGE₂ treatment selectively expands the MPP subset of LSK cells. (A) Flow cytometric dot plot illustrating gating scheme for subsets of LSK cells using Flt3 and Thy1.1 surface markers with a parent population of Lin⁻ Sca1⁺ c-Kit⁺. (B-E) Flow cytometric analysis of the frequency of LSK cells (B), MPPs (C), ST-HSCs (D), and LT-HSCs (E) in the bone marrow after PGE₂ or vehicle treatment. *P ≤ .05, **P ≤ .01 (3 separate experiments are included).