Figure 7. Schematic diagram of signaling pathways involved in the hypertrophy of ligamentum flavum. Intracellular ROS accumulated during the aging process and after repetitive mechanical stress in vivo, and the condition was simulated by hydrogen peroxide treatment in the current study. The upregulated oxidative stress subsequently activated Akt, JNK, and p38 MAPK pathways and triggered inflammation as well as fibrosis. Accumulation of fibrotic extracellular matrices eventually resulted in hypertrophy of the ligamentum flavum.