Long-term FLAG expression is seen in BM (BM) cells of rats injected with SV(Nef-FLAG). Rats given SV(Nef-FLAG) or SV(BUGT), as a control, intrafemorally, at 2 × 10¹¹ IU/rat. They were killed at the end of the 16.5-month follow-up period. BM cells obtained by flushing both femurs were treated to lyse red blood cells, after which the nucleated cells were immunostained for either FLAG or FLAG + granulocyte markers. Transgene expression was detected by FACS and analyzed as described in “Materials and methods.” (A) Representative dot plots for FLAG expression in BM cells, here from rats no. 5 and no. 6, as well as a contemporaneous control rat (CT). FSC = forward scatter. The proportions of FLAG⁺ cells as a percentage of total nucleated cells are shown. (B) Representative FACS dot plots for FLAG expression in BM granulocytes in the same rats. Percentages of FLAG⁺ granulocytes shown are relative to total granulocyte⁺ cells.