Figure 4

ATF3 suppresses Sox9-dependent transcription and stimulates Runx2-dependent transcription. Primary chondrocytes were cotransfected with SOX9 (A) or RUNX2 (B) reporter plasmids, pcDNA3 (control) or an ATF3 expression vector, and pRLCMV. 24 hours after transfection, cells were harvested, firefly luciferase activity was measured and normalized to Renilla luciferase activity. Data represent averages and SEM from three independent experiments, performed in quadruplicate each (*: p < 0.05). ATF3 overexpression suppressed SOX9-dependent transcription and stimulated RUNX2-dependent transcription.