EGFR and cancer: The Wnt/β-catenin and RAS-ERK pathways are major pathways involving human cancers, and abnormalities in these two pathways genes are well characterized, such as APC and CTNNB1 (the gene encoding β-catenin) mutations in the Wnt/β-catenin pathway and RAS, RAF, and upstream epidermal growth factor receptor (EGFR) mutations in the RAS-ERK pathway have been known to play important roles in the tumorigenesis.