Based on limited published evidence, KRT39 is a type II keratin protein involved in intermediate filament organization and epithelial cell differentiation. UniProt annotations indicate a potential role in late hair differentiation. KRT39 localizes to the cytoskeleton and cytoplasm and functions as a structural constituent of skin epidermis. Genome-wide analysis in yak identified KRT39 within a module associated with hair follicle development and keratinocyte proliferation 1. KRT39 gene amplification has been detected in HER2-positive gastric cancer samples 2, though the functional significance in cancer remains unclear.