Comparable relaxation into a mono-stable off state was observed in many parallel experiments, including: (i) infections with LTR-GFP-IRES-Tat, LTR-Tat-IRES-GFP, or LTR-mRFP-IRES-Tat-GFP viruses eventually relaxed into a GFP off state; (ii) GFP+ cells of each of these infections, isolated by bulk FACS, eventually relaxed into an off state; and (iii) GFP+ cells of each of these infections isolated by single-cell (i.e., clonal) FACS analysis eventually relaxed into an off state (unpublished data). This evidence concerns the gene TAT and infection.