DNA microarrays are created by spotting every gene in a genome onto a glass microscope slide.
RNA is isolated from two populations of cells. Two populations of RNA are converted to two colors (red and green) of cDNA.
cDNAs are hybridized with the microarray.
Microarray is washed and scanned for red and green cDNA.
Spots that bind to both cDNAs appear yellow.
Examples of real data.
