To evaluated the role of miR-221 and E-cadherin in mediating breast cancer metastasis in mouse model, we first designed and generated four types of modified MDA-MB-231 cell lines: cells infected with control lentivirus (control), cells stably transfected with WT E-cadherin (E-cad (WT)), cells stably transfected with WT E-cadherin combined with anti-miR-221 (E-cad (WT) plus anti-miR-221), and cells stably transfected with MUT E-cadherin (E-cad (MUT)). Here, CDH1 is linked to breast carcinoma.