NCIt definition : Human TK1 wild-type allele is located within 17q23.2-q25.3 and is approximately 13
kb in length. This allele, which encodes thymidine kinase, cytosolic protein, plays
a role in phosphorylation of thymidine to form deoxythymidine monophosphate. The TK1
gene is amplified in breast ductal carcinomas and overexpressed in other types of
cancer such as colon cancer and thyroid carcinomas.;