Intermediate filaments (IFs) are a structurally related family of cellular proteins that appear to be intimately involved with the cytoskeleton. Human keratin 18(KRT18) and the homologous mouse Endo B are type I IF protein subunits whose expression is restricted in adults to a variety of simple epithelial tissues. The KRT18 gene is 3,791 bp long and the keratin 18 protein is coded for by 7 exons. The K18 gene is 3791 bp in length and the K18 protein is coded for by seven exons. By Southern blotting using the genomic DNA PCR product, the gene for keratin 18 is assigned to chromosome 12. Mutation of human keratin 18 in association with cryptogenic cirrhosis.