KRT81 (keratin 81) is a hair keratin protein that functions as both a structural component and regulator of cellular processes across multiple tissue types. As a structural constituent, KRT81 contributes to keratinization and intermediate filament organization in skin epidermis 1. Beyond its structural role, KRT81 acts as a protein scaffold that facilitates cellular migration and invasion by interacting with ezrin, a member of the ezrin/radixin/moesin protein family that regulates cell morphology and motility 2. In breast cancer cells, KRT81 promotes invasiveness by enhancing matrix metallopeptidase (MMP)9 activity and cell migration capabilities 3. The protein demonstrates significant clinical relevance across multiple cancer types, where elevated KRT81 expression correlates with poor prognosis in pancreatic ductal adenocarcinoma, colorectal cancer, and triple-negative breast cancer 456. In triple-negative breast cancer, KRT81 appears to suppress CD8+ T cell activity and influence immunotherapy responses 6. Disease associations include monilethrix, where mutations in related hair keratins cause hair shaft abnormalities 1. Additionally, genetic variants in KRT81 serve as prognostic markers, with specific SNPs associated with survival outcomes in non-Hodgkin's lymphoma 7.