Resolution of structural variation detection by ESP has been increased to the similar level as PCR, and can be further improved by selection of more evenly sized DNA fragments. ESP can be applied for either with or without constructed artificial chromosome. With BAC, precious samples can be immortalized and conserved, which is particularly important for small quantity of smalls which are planned for extensive analyses. Furthermore, BACs carrying rearranged DNA fragments can be directly transfected in vitro or in vivo to analyze the function of these arrangements. However, BAC construction is still expensive and labor-intensive. Researchers should be really careful to choose which strategy they need for particular project. Because ESP only looks at short paired-end sequences, it has the advantage of providing useful information genome-wide without the need for large-scale sequencing. Approximately 100-200 tumors can be sequenced at a resolution greater than 150kb when compared to sequencing an entire genome.