The process by which proteins are degraded in cells is called proteolysis. This process involves breaking down proteins into smaller peptides or amino acids, which can then be reused for various cellular functions, including energy production or synthesis of new proteins. Proteolysis is facilitated by enzymes known as proteases, and it plays a crucial role in maintaining cellular homeostasis, regulating metabolic pathways, and eliminating misfolded or damaged proteins that could harm the cell.