(A.) Graphs show the normalized permeability responses in HPAECs that were transfected with non-targeting (NT) or Cx43 (si) siRNAs for 48 hr and then left untreated or treated with 0.5 U/mL thrombin for 3 hr. (NT+thr and si+thr). Permeability response is given as (1– minimum normalized TER), where normalization is to TER at time point just prior to the first treatment. **, p<0.001. *, p<0.05. n = 8 for NT or siRNA alone; n = 11 for NT+thr group; n = 13 for si+thr group. (B.) Graphs show the normalized permeability responses in Pulmonary Microvascular Endothelial Cells (PMVECs) that underwent identical siRNA transfection and thrombin treatment. **, p<0.001. n = 3 for NT+thr and si+thr groups; n = 4 for NT group; n = 3 for si groups. (C.) HPAECs were transfected with Cx43 or control siRNA for 48 hr, treated with thrombin (0.5 U/mL; 30 min) and collected for Western Blot. Phospho-MLC protein was normalized to β-actin relative to control. *, p<0.05. n = 6 for each condition. (D.) Graphs show the normalized permeability responses in siRNA-transfected HPAECs that had been treated with 200 ng/mL lipopolysaccharide (LPS) for 24 hr. **, p<0.001. n = 7 for each group. NT = non-targeting siRNA, si = siRNA-Cx43. Thr = thrombin.