EGFR and cancer: For example, since epidermal growth factor (EGF) is upregulated in numerous cancer cell types, tags have been engineered and tested as fusions to the C-terminus of MVP to facilitate targeting to epithelial cancer cells via the EGF receptor (EGFR): a 33 amino acid Fc-binding peptide (called the Z domain) and the 55 amino acid epidermal growth factor (EGF).