Thus, we searched the possible candidate genes in the Tcas3 region using microarray analysis of TCs in F1 rats and revealed significant upregulation of 2 cancer-related genes, parathyroid hormone-like hormone (Pthlh) and Kras2. The relevance of the WF allele of Pthlh as a cancer modifier was indicated by 3 single nucleotide polymorphisms specific to this strain. Here, KRAS is linked to cancer.