Furthermore, the fact that both heterozygous and homozygous Krt18-deficient mice demonstrate chromosomal instability and increased tumor incidence suggests that it is not caused by the absence of the Keratin IF cytoskeleton (which is only the case in homozygous Krt18-deficient mice) but rather the imbalance of Type I and Type II keratin expression. This evidence concerns the gene KRT18 and neoplasm.