Fig. 4. Impact of acetaldehyde on ALDH2*1/*2-OBs: oxidative stress and altered TNFα, OPG, and RANKL levels. (A) Quantification of TNFα, OPG, and RANKL expression in OBs treated with or without 4 mM acetaldehyde. (B) Protein expression of 4HNE, TNFα, OPG, and RANKL in OBs with or without 4 mM acetaldehyde. GAPDH was used as a loading control. (C) Quantification of western blot results using the Adobe Photoshop. (D) Calculation of OPG and RANKL ratio based on quantified western blot results. (E) Measurement of TNFα in the cultrued medium of each group. Data are presented as the mean±SEM. ^#p<0.05, ^##p<0.01, ^###p<0.001 (t-test), *p<0.05, ***p<0.001 (two-way ANOVA) indicate statistical significance. TNFα: tumor necrosis factor α, OPG: osteoprotegerin, 4HNE: 4-Hydroxynonenal, OBs: osteoblasts.