Figure 4. The activity of nuclear factor-κB (NF-κB) was assessed by immunofluorescence for NF-κB p50 and phosphorylated NF-κB p50 (pNF-κB p50). Oxidative stress was induced by exposure to 20 μM of H₂O₂ for 16 h. In the maltol treatment group, 1 mM of maltol was added to the culture medium at the time of injury. A: Undamaged control; B: Oxidative stress only; C: Oxidative stress with maltol treatment. Unphosphorylated inactive NF-κB was labeled with red fluorescence and phosphorylated active pNF-κB was labeled with green fluorescence. Scale bar represents 25 μm.