If in some models P-cadherin has been suggested to act as an invasion suppressor, such as in colorectal cancer [27] or in melanoma [28], in several other models, including breast cancer, P-cadherin behaves as an oncogene, inducing increased tumour cell motility and invasiveness when aberrantly overexpressed [12]–[14], [27], [29]–[31]. This evidence concerns the gene CDH3 and breast cancer.