The DSCAM gene in the brain is also spliced in multiple steps to allow a huge complexity of proteins to be made. The Dscam gene contains 95 alternative exons that are organized into four clusters of 12, 48, 33, and 2 exons each. Each protein picks an exon from each cluster, yielding 38,016 possible forms. It is probably used to tag cells with a surface marker not expressed by neighboring cells.