The Affiliated Zhangjiagang Hospital of Soochow University 1 article published in JoVE Biochemistry Purification of Ubiquitinated p53 Proteins from Mammalian Cells Di Wu1, Mengfan He1, Dawei Li1 1Center for Translational Medicine, The Affiliated Zhangjiagang Hospital of Soochow University The protocol describes a step-by-step method to purify ubiquitinated proteins from mammalian cells using the p53 tumor suppressor protein as an example. Ubiquitinated p53 proteins were purified from cells under stringent nondenaturing and denaturing conditions.