Representatives for LTR and RBC did not immediately respond to requests for comment.

LTR-retrotransposons have been reported in many diverse eukaryote species, describing a ubiquitous distribution.

Functional activity of Tat was assessed using an LTR transactivation assay.

The polyadenylation signal for the transcript is provided by the inserted LTR sequence.

Transgenic mice harboring an active LTR driving lacZ expression were generated and analyzed.