In 2003, Mu et al. [77] described KCNK9, the gene encoding K2P9.1, as a potential proto-oncogene where genomic overexpression of the gene was detected in 10% of breast carcinomas and the protein was detected in 44% of breast tumours by immunohistochemistry but not in normal tissue controls. This evidence concerns the gene KCNK9 and breast neoplasm.