Microspots of proteins immobilized on solid support and exposed to samples of binding molecules. In such a system, enzyme–substrate and protein–ligand relations can be visualized by the use of fluorescence, chemiluminescence, mass spectrometry, radioactivity, or electrochemistry.  protein chips,  protein profiling,  antibody microarray,  chemiluminescence,  fluorescence,  mass spectrum; Templin MF et al 2002 Trends Biotechnol 20:160.