Department of Pathology, The Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD 21287, USA. jboeke@jhmi.edu
Long interspersed nuclear elements (LINEs) are among the most successful parasitic genetic sequences in higher organisms. Recent work has discovered many instances of LINE incorporation into exons, reminding us of the hazards they pose to genes in their vicinity as well as their potential to be co-opted for the host's purposes.