Eye and ENTHospital of Fudan University 1 article published in JoVE Biology In Vivo Detection and Analysis of Rb Protein SUMOylation in Human Cells Fengxi Meng*1,2, Xiaofeng Li*1,2, Hui Ren1,2, Jiang Qian1,2 1Department of Ophthalmology, Eye and ENT Hospital of Fudan University, 2Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University Small ubiquitin-related modifier (SUMO) family proteins are conjugated to the lysine residues of target proteins to regulate various cellular processes. This paper describes a protocol for the detection of retinoblastoma (Rb) protein SUMOylation under endogenous and exogenous conditions in human cells.