CD274 and breast cancer: The specific mechanism [103] may be that miR-424-5p enhances the chemosensitivity of MDA-MB-231 breast cancer cells by regulating the PD-L1 and PTEN/mTOR axes and apoptosis-related factors, including p53, caspase 3, Bcl-2, and Bax, and the proliferation-related gene c-Myc.