To assess the functional role of E-cadherin and P-cadherin in invasive breast cancer, we first transfected 231 cells with a constitutively activated expression vector (pCDNA3) containing either the complete human E-cadherin or P-cadherin cDNAs (kindly provided by Dr Setsuo Hirohashi, Tokyo, Japan) [26]. Here, CDH1 is linked to breast cancer.