The FluoroSpot Assay is a variation of the ELISpot assay. Enzyme-linked immunosorbent assay (ELISA) also detects antigens. This may be with a laboratory test of the ELISA (enzyme-linked immunosorbent assay) type. The antigenicities were measured through an enzyme-linked immunosorbent assay (ELISA). Commonly used tests include chromatography, immunologic assay, and mass spectrometry. ATCC also serves to set standards for biological reagent and assay quality. The von Willebrand factor is undetectable in the vWF antigen assay. This is more accurate than cytotoxigenic culture or cell cytotoxicity assay. It can also be achieved through indirect immunofluorescence assay. Specificity of this assay for detecting schistosome infection is 99%. Differential display, RNase protection assay and northern blot. This effect can interfere with the estimation of protein concentration using the Bradford assay. Protein shuttling can be assessed using a "heterokaryon fusion assay". An assay (analysis) is never an isolated process. GFP has been shown to be useful in cryobiology as a viability assay.