National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA. schuler@ncbi.nlm.nih.gov
A crucial event in the history of the Human Genome Project was the decision to use sequence-tagged sites (STSs) as common landmarks for genomic mapping. Following several years of constructing STS-based maps of ever-increasing detail, the emphasis has recently shifted towards large-scale genomic sequencing. A computational procedure called 'electronic PCR' allows STS landmarks to be revealed as data emerge from the sequencing pipeline, thereby bridging the gap between mapping and sequencing activities.