Centro Cardiologico Monzino 1 article published in JoVE Biochemistry Optimized Protocol for the Extraction of Proteins from the Human Mitral Valve Cristina Banfi1, Anna Guarino2, Maura Brioschi1, Stefania Ghilardi1, Valeria Mastrullo1, Elena Tremoli1, Gianluca Polvani2,3,4 1Centro Cardiologico Monzino IRCCS, 2Cardiovascular Tissue Bank of Milan, Centro Cardiologico Monzino IRCCS, 3Department of Clinical Sciences and Community Health, Cardiovascular Section, University of Milan, 4Department of Cardiovascular Disease, Development and Innovation Cardiac Surgery Unit, Centro Cardiologico Monzino IRCCS The protein composition of the human mitral valve is still partially unknown, because its analysis is complicated by low cellularity and therefore by low protein biosynthesis. This work provides a protocol to efficiently extract protein for the analysis of the mitral valve proteome.