Inactivation of Mef2c results in reduction of monocytic progenitors. (A) PCR of genomic DNA isolated from BM used for analysis to verify the presence of an excised allele (Δ), the loss of the floxed allele (fl) after excision, and a deleted allele (−) from the constitutively inactivated allele. As controls (last 3 lanes), nonhematopoietic DNA was analyzed that has not been subject to CRE recombinase. (B) BM from Mef2c^fl/− MxCRE or Mef2c^+/+ MxCRE littermates, all subjected to pI/pC treatment, was subjected to FACS analysis to determine the relative levels of early myeloid compartments within the Lin^- population. Shown is the mean and standard deviation (n = 3). (C) To determine the level of committed GM progenitors, BM cells were also analyzed in a myeloid colony assay. Colony number and morphology were scored 1 week after plating. Shown is the result of one experiment performed in triplicate. Error bars denote standard deviation from the mean. Experiment was repeated 4 times with similar values. (D) FACS analysis and stained cytospins of cells dispersed from methylcellulose cultures demonstrate the relative loss of macrophages (CD11b⁺/F4-80⁺) in differentiating cultures of BM cells lacking active Mef2c. (E) The proportion of monocytic cells (CD11b⁺/Gr1⁻) relative to granulocytes (CD11b⁺/Gr1⁺) cells is consistently decreased in the blood of Mef2c^Δ/− mice relative to Mef2c^+/+ mice (n = 5). Error bars denote standard deviation from the mean.