OA-induced NOX4 and ROS production are regulated by ANGPTL4 in CRC cells. (A-B) ROS levels were analyzed by flow cytometry analysis with DCFDA staining in SW480 cells transfected with 20 nM siANGPTL4 (siANG#1 and #2), SC siRNA, or expression vector of ANGPTL4 (flANG) and then treated with or without 200 µM OA and 5 mM NAC for 24 h. Quantification of ROS intensities is shown in columns (i). BG indicates background. ELISAs were performed to assess ANGPTL4 secretion in SW480 cells (ii). Vec indicates empty vector. (C-E) Real-time quantitative PCR and immunoblotting analyses for NOX4 and ANGPTL4 mRNA and protein levels, respectively were performed in SW480 cells transfected with 20 nM siANGPTL4 (siANG#1 and #2), siNOX4, and SC siRNA (C, E), or expression vectors of full-length (flANG), C-terminal (cANG), and N-terminal (nANG) ANGPTL4 (D), and then treated with or without 200 μM OA and 5 mM NAC for 16 h. Real-time quantitative PCR and western blotting were performed to examine NOX4 mRNA and ANGPTL4 protein levels, respectively (D). NS indicates not significant. The data are presented as the mean ± SEM. P-values were determined using a two-tailed Student's t-test. ***P < 0.001 (n=3).