Does the presence of casein in the blocking solution matter for IHC experiments?

Reagents that contain casein, such as milk, may result in a reduced signal or lack of signal with some antibodies in IHC (most notably with phospho-specific antibodies). Therefore, casein in the blocking solution for IHC may be problematic. Given this, we routinely block in 1X TBST+5% Normal Goat Serum #5425 (NGS) or Animal-Free Blocking Solution (5X) #15019 when performing IHC experiments.

Last updated: August 3, 2025