PGR and obstructive sleep apnea syndrome: Examination of the effect of hypoxia (1% oxygen) and desferrioxamine (DFO), a hypoxia mimetic which promotes the accumulation of HIF transcription factors, on OSA cells demonstrated that PR expression was significantly elevated in response to 1% oxygen at 24 h in cell lines 529 and 484 (Figure 3); there was a trend for increased PR expression cell line 617 (p < 0.36).