distinct structure and properties, keratins have been classifed as ‘soft’ and ‘hard’. Soft keratins are those found as IF in epithelia, are arranged in loosely packed bundles, and are responsible for the mechanical resilience of epithelial cells. Hard keratins are those foundin ordered arrays in matrices of cysteine-rich proteins in hairs, nails, claws and beaks, and contribute to the tough structure of epidermal appendages [3, 4]. Based on their structure, keratins can also be classifed as α-keratins or β-keratins