A reference library of 2,000,000 microbeads was formed by mixing equal numbers of microbeads with attached cDNA derived from induced and noninduced THP-1 cells. Reference microbeads (100,000) were hybridized with 10 μg each of Cy5-labeled probe and R110-labeled probe, both derived from the same induced library to yield A. Microbeads (1,600,000) were hybridized with 10 μg of Cy5-labeled probe from the induced library and 10 μg of R110-labeled probe derived from the noninduced library to yield B.