Knockdown of c-Fos, Fra-2, c-Jun, or JunD decreases expression of Foxp3. A. Expression levels of c-Fos, Fra-2, c-Jun, or JunD after transfection with siRNA; B. Expression levels of Foxp3 after knockdown of c-Fos, Fra-2, c-Jun, or JunD. Foxp3, forkhead/winged helix transcription factor p3; siRNA, small interference RNA.