Mut10-expression alters the kinetics but does not block the differentiation of murine BM cells. (A-C) Giemsa-stained cytospins of liquid cultures maintained for 14 days after infection with either control FMEV-GFP (A), FMEV-mut10 (B), or MPEV-CRE vectors (C) in SCF, IL3, FLT3, and IL11. (A) Cultures infected with a control vector consist predominantly of macrophages and mast cells, typical for the end-stage of long-term cultures of hematopoietic cells. (B) Cells infected with the FMEV-mut10 vector display a spectrum of maturing monocytes/macrophages and promyelocytes/metamyelocytes. (C) Cells lacking C/EBPα due to recombination of the conditional gene targeted alleles remain in an undifferentiated myeloblastic or early promyelocytic stage. Original magnification, × 560.