Fig. 4.

Apical H₂O₂ production in HBE1 and TBE cells treated with or without ATRA. HBE1 cells (A) and primary TBE cells (B) were grown in ALI culture conditions with or without 30 nM ATRA for 7 days followed by measurements of H₂O₂ using Amplex Red assays: M, media alone; D, diphenyleneiodonium (20 μM); T, thapsigargin (1 μM); and T,D, thapsigargin/diphenyleneiodonium cotreatment. Values are expressed as nM H₂O₂/well/10 min by comparing with an H₂O₂ standard curve. Data represent the means and SE of 3 independent experiments with 9 wells per treatment group. ***P < 0.0001 (by ANOVA).