Reduced APC2 has also been implicated in breast cancer through loss of heterozygosity,24, 25, 26 allelic imbalance17 and promoter hypermethylation.27 As both APC proteins can regulate Wnt signaling, both are expressed in mammary epithelium and loss of either has been linked with breast cancer, there is a possibility that functional redundancies exist in this tissue as they do in Drosophila development,28 but this has yet to be proven. This evidence concerns the gene APC and breast cancer.