AMPK and PRODH/POX expression (A), ROS formation (B), and cell membrane integration (C) in C32 and C32POX− cells treated with metformin (0–20 mM, MET) for 24 h. THFA (PRODH/POX inhibitor) was used at a concentration of 200 µM. Representative Western blot images were shown (the mean values of densitometric analysis after GAPDH normalization as a ratio versus control were presented below each blot). Supplementary Materials contain statistical analysis of the evaluated proteins (Supplementary Material, Figures S1 and S2). The mean values with standard deviation (SD) from 3 experiments performed in duplicates are presented. Asterisks * indicate statistical differences between studied cells compared to controls at p < 0.001. C—control, THFA—tetrahydrofuroic acid, MET—metformin.