We mapped 300 kb of DNA sequence flanking the H11 locus in the human genome utilizing the UCSC database and found that there were no cancer genes present in the region and only one microRNA, 288 kb distant from H11. In these respects, H11 compares favorably with the current widely used loci for transgene insertion in human cells, ROSA26, AAVS1 and HPRT1, all of which are in exons or introns of endogenous genes and are differentially expressed in different tissues (28). Here, HPRT1 is linked to cancer.