MN1 and CD34 expression during in vitro differentiation of CD34⁺ progenitor cells. Real-time RT-PCR was performed on days 0, 4, 8, 12, and 16 of in vitro differentiation using differentiation-inducing growth conditions (G-CSF, M-CSF, or EPO) or maintenance culture conditions with lineage-unspecific cytokines (SCF, TPO, FL ± IL-6). Mean ± SD is shown for 3 independent experiments. Expression of MN1 and CD34 in CD34^– cell populations was analyzed at day 0. (A) MN1 expression levels during in vitro differentiation. (B) CD34 expression levels during in vitro differentiation. Giemsa staining of cytospin preparations shows typical morphologic features of granulocytic (G-CSF; C), macrophage (M-CSF; D), and erythroid (EPO; E) maturation.