Cell surface markers of MODP and MOP. (A) Hypothetical positioning of the MODP and MOP in the hematopoietic tree. (B) Overview of cell surface marker expression on LMPP, CLP, GMP, MODP, and MOP according to literature data (black) and according to our own flow cytometric analysis (red) (*marker present on <10% of the population). (C) Expression of indicated cell surface markers on MODP and MOP populations according to flow cytometry. (D) Phenotypic definition of CD27^high MODP (upper quadrants) and CD27^low MOP (lower quadrants) populations within B220⁻CD11b^low/−c-Kit⁺c-Fms⁺ BM cells and their cell surface Flt3 expression according to flow cytometry. (E) Relative Flt3 mRNA expression, as determined by quantitative polymerase chain reaction in the indicated subsets of B220⁻CD11b^low/−c-Kit⁺c-Fms⁺ BM cells. Data are representative of 2 experiments with n = 3. Error bars indicate standard deviations. Ctrl, control (unstained); max, maximum; n/a, not applicable.