This antiserum serves as an exceptional tool for investigating terminal epidermal differentiation. It interacts with epidermal cells in the uppermost suprabasal layers, including the scalp, foot, and sole. It identifies individual cells within the epidermis of the tongue and nipple, co-localizing with keratin K1. It also demonstrates robust reactivity on hyperkeratosis of various origins. Notably, it does not react with palate keratin K76. The reactive polypeptide is basic human keratin K2, with a molecular weight of 65,852, previously known as cytokeratin 2e.