Non-fat powdered milk is one of the most commonly used blocking agents in a variety of applications, including Western blots, IHC, and ELISA. It can also be used as antibody diluent during both primary and secondary antibody incubations to reduce non-specific binding and overall background in Western blots. Since non-fat powdered milk contains phosphoproteins, it is not recommended as a blocking agent when the target antigen is a phosphorylated protein, as its use may result in high background.