Figure 5.

SV40 enhancer blocking function by the sns fragment in human cell lines. The plasmid constructs A–E were transfected into HeLa cells and in the osteosarcoma cell line U-2 OS. Detection of the CAT enzymatic activity on cellular extracts were performed 48 h after transfection. CAT refers to an enzymatic reaction carried out by using 1.2 units of a commercial chloramphenicol acetyltransferase. The autoradiogram shows the thin-layer chromatographic separation of [¹⁴C]chloramphenicol and its acetylated derivatives.