Human tiling arrays are designed by dividing the non-repetitive sequence of a genomic region or regions into contiguous 35 base pair units. A 25-mer is designed from each of these units (Promoter and Whole Genome arrays) or overlapping 7 base pair (ENCODE array) or 16 base pair (Chromosome 21/22 array) units The collection of these 25-mers comprises a tiling array. The arrays are useful for the localization of the genomic binding sites of transcription factors and other chromatin associated proteins. In addition to the human arrays (ENCODE, chromosome 21/22, promoter, whole genome), mouse arrays (promoter, whole genome), whole genome arrays for c.elegans, drosophila, s.cerevisiae, s.pombe and arabidopsis are also available.

The process is as follows: an investigator performs chromatin immunoprecipitation, uses LM-PCR to amplify the DNA that has been extracted from the immunoprecipitate, fragments and biotinylates the PCR products, then submits those products to the Microarray Core for hybridization, staining and scanning.