Intermediate filaments are medium-sized protein filaments that form an integral part of the cytoskeleton. They perform several functions including: 

• Providing cells with much-needed structure, support, and mechanical stability
• Serving as flexible intracellular tendons that prevent cells from excessive stretching when theyare subjected to external or internal physical forces
• Anchoring a cell to other cells and to the extracellular matrix, which allows cells to form tight barriers and remain cohesive even under tension, which is particular important for epithelial cells