PCNA and breast cancer: The results indicated that in the MCF-7 human breast cancer cell line, E2 and curcumin decreased cell proliferation and the colony-forming capacity and down-regulated protein expression as well as important molecules associated with cell proliferation, such as PCNA and estrogen receptor alpha; genes associated with the epithelial-mesenchymal transition, such as β-catenin, Vimentin, and E-cadherin; and molecules associated with apoptosis.