Figure 2: Rab25 regulates OPG expression. A) QPCR measurement of OPG and Rab25 mRNA level in HEY cells. *, p < 0.001 vs pcDNA control. (B) Effect of siRNA on OPG and Rab25 mRNA expression. Ovarian HEY cells were transfected with siRNA specific to OPG or Rab25, as well as non-target siRNA (NT) control. Samples were collected 24h post transfection and mRNA expression level was detected with QPCR (data are from one of three representative experiments). (C) Reduction of OPG production after siRNA knockdown expression of OPG and Rab25. OPG secretion in media was measured using Human Osteoprotegerin (OPG)/TNFRSF11B DuoSet purchased from R&D Systems. p < 0.05 vs NT siRNA control. (D) Knockdown expression of OPG and Rab25 by siRNA increase TRAIL sensitivity. Cells were transfected with siRNA specific to OPG, Rab25 or non-target siRNA (NT) for 24h, then media were changed in the present of 100ng/ml of TRAIL for 24h before assay. a, p < 0.01 vs no drug NT siRNA transfected control, b p < 0.05 vs NT siRNA transfected TRAIL treated samples. E) Addition of 100ng/ml of exogenous OPG blocks 100ng/ml TRAIL-induced cell death. a, p < 0.05 vs no drug treatment. b, p < 0.05 vs 100 ng/ml TRAIL treatment only. (F) Pretreatment cells with 10mM of Brefeldin A (BFA) or Monensin block OPG secretion. a, p < 0.01 vs HEY pc DNA control, b, p < 0.001 vs HEY Rab25 control.