Objective To explore the role of cancerous inhibitor of protein phosphatase 2A(CIP2A) in the malignant transformation of breast ductal epithelium and its association with the prognosis of breast ductal cancer.Methods Immunohistochemistry staining was used to detect CIP2 A protein in 322 paraffin-embedded breast samples including normal breast duct,usual ductal hyperplasia(UDH),atypical ductal hyperplasia(ADH),ductal carcinoma in situ(DCIS) and invasive ductal carcinoma(IDC).Chi-square test was used to asses...