FIG. 4.

Influence of various HPV-16 L1 ORFs on the expression of a downstream-located GFP gene in a bicistronic expression construct. Cells were transfected with expression constructs containing genes encoding L1h, L1p, and L1ori, or a non-L1 gene (the ecotropic retrovirus receptor gene rec1) upstream of an IRES-GFP cassette. Expression of GFP was analyzed by FACS analysis (a) and Western blotting (b). Note that the total fluorescence of the rec1-GFP-transfected cells was set to 100%. (c) Western blot analysis of L1 expression levels in the same extracts as for panel b.