Overexpression of Id genes in BMMs does not affect the expression level of characteristic dendritic-cell markers. BMMs were transduced with pMX-IRES-EGFP (control), Id1, Id2, or Id3 retrovirus. Cells were cultured for 4 more days with GM-CSF to generate DCs. LPS (1 μg/mL) was added to cultures to induce DC maturation. The cells were harvested the next day and stained for FACS analysis with anti-CD86, anti-CD11b, anti–I-A^b, anti-CD11c antibodies (solid line), or control IgG (dotted line).