Downregulation of the UNG2 protein is independent of Vpr binding and Vpr-induced G2 arrest. (A) Immunofluorescence analysis of UNG1/2 expression in Vpr-expressing cells. At 24 h after transfection with vectors encoding wild-type, mutated HA-Vpr proteins or with the empty plasmid (mock), cells were analyzed by immunofluorescence as indicated in Fig. 2 with anti-HA (upper panels) and anti-UNG (PU59) (middle panels) antibodies. (B) Quantification of cell number defective for UNG2 expression among the transfected cell population. The number of cells with a reduced nuclear UNG2 staining was quantified over 100 cells expressing HA-Vpr, HA-IN, or the empty plasmid (mock). On the left side, the results are expressed as the percentage of cells showing defective nuclear UNG2 staining among the transfected cell population. Values are the means of three independent experiments. On the right side, ratio of UNG2/UNG1 expression quantified from transfected cells. Number of transfected cells expressing a nuclear UNG2 staining was divided by number of cells expressing a cytoplasmic UNG1 signal. Values are the means of three independent experiments. (C) The number of cells with a reduced nuclear UNG2 staining was quantified over 100 cells expressing wild-type or mutated HA-Vpr proteins. The results are expressed as indicated in panel B. Values are the means of three independent experiments. WT, wild type.