immunoblot in-cell western assay The In-Cell Western Assay is an immunocytochemical assay that uses NIR fluorescence to detect and quantify proteins in fixed cells. Detecting proteins in their cellular context increases quantification precision. Proteins in fixed, cultured cells are detected directly in microplates, which yields higher throughput compared to Western blotting and eliminates typical Western blotting steps such as cell lysate preparation, electrophoresis, and membrane transfer. Using the In-Cell Western Assay kits, the cost per well for secondary screening is reduced to a fraction of the cost of typical western blots.