Protein, the organic macromolecule, is the main undertaker of life activities. Proteins have a variety of functions in living organisms, including catalysis, locomotion, transportation, mechanical support and protection, immunity and defense, regulation, etc. Proteins are the kind of biomolecules that have been studied the most. In vitro studies related protein are mostly applied to purified proteins, while in vivo studies focus on the activity of proteins in cells or whole tissues. Reagents supplied by Yeasen mainly focus on protein analysis, involving protein electrophoresis, protein quantitation, western blot, and IP & CO-IP.