Figure 6 C1q/tumor necrosis factor-related protein 13 (CTRP13) restored mitochondrial functioning by counteracting oxidized low-density lipoprotein (ox-LDL) effects on the AMPK/KLF4 pathway. The following groups were assessed: (1) Control; (2) ox-LDL; (3) ox-LDL + CTRP13; (4) ox-LDL + CTRP13 + compound C; and (5) ox-LDL + CTRP13 + APTO. (A) Representative fluorescent images of DCFH-DA probe and (B) quantification of intracellular reactive oxygen species (ROS) levels in 5 cell groups. (C) Representative fluorescent JC-1 images for testing the mitochondrial membrane potential in human umbilical vein endothelial cells (HUVECs), aggregates shown in green, and monomers shown in red (scale bars=100 μm). (D) Quantitative analysis of the aggregates to monomers ratio. (E, F) Intracellular glutathione peroxidase 4 (GPX4) levels were depicted by representative immunofluorescence images. The data are expressed as the mean±SD (n=3–4 per group). Statistical power=0.972987, effect size(r)=0.914731. * P<0.05 vs the control group. # P<0.05 vs the ox-LDL group. Fluorescent images were evaluated using Olympus fluorescence microscopy with cellSens Dimension software (Version 1.3 rev, Olympus, Tokyo, Japan), and the positive cells were measured by Image Pro Plus 6.0 (Media Cybernetics, Rockville, MD, USA). GraphPad Prism 9.0 software (La Jolla, USA) was used to analyze the data.