Expression of E5 protein in vitro and cell line mRNA. (A) Autoradiographs of PAGE gels containing in vitro wheat germ protein translation products of HPV-16 E5 variants (G) and 'stop' codon controls (S), demonstrating 35S-labelled 9.1 kDa products in the former, but not the latter. +: positive (luciferase), and -: negative kit controls. X: 1 ng HPV-16 RNA ; Y: 0.1 ng HPV-16 RNA. (B) Expression of E5 mRNA detected by RT-PCR in transfected cell-lines analysed in the presence (+) or absence of reverse transcriptase. B: blank.