MINOR expression is highly up-regulated in activated DC populations in vitro and in vivo, and its forced expression induces apoptosis in DC2.4 cells. (A) Day-4 BM-derived CD11c⁺ cells (D4 CD11c⁺), immature (D8 CD11c⁺MHC^lowCD86^low), and activated (D8 CD11c⁺MHC II^highCD86^high) BMDCs were FACS-sorted and examined for their expression of MINOR, Nur77, and Nurr1 using real-time quantitative RT-PCR as described in “Quantification of transcripts.” Transcript levels were normalized to β-actin. Expression levels are expressed as fold increase compared with those of activated macrophages. (B) The results of experiments in which mice were injected with vaccinia virus to induce activation in vivo, and splenic DCs were then sorted based on their expression of CD86, CD11c, and B220 into naive and activated populations of conventional or plasmacytoid DCs, which were then analyzed for MINOR expression by quantitative PCR. Transient expression of MINOR induced DC2.4 apoptosis. GFP-control (left panel) and GFP-MINOR-expressing (right panel) DC2.4 cells were analyzed for apoptotic markers using FACS analysis, shown in panel C. A representative FACS plot of annexin V versus 7-AAD staining is shown along with a statistical analysis of results of 3 different experiments. *P < .05, analysis of variance or t test.