PRKN and breast cancer: In BC, the p53 gene (TP53) is inactivated by mutation in over half of all human cancers [8] or by overexpression of its negative regulator, the mouse double minute 2 (MDM2) oncoprotein, an E3 ubiquitin ligase, that triggers p53 degradation through a ubiquitin proteasome-dependent pathway [74].