Fig. 2. HPV-16 E6/E7 expression. RT-PCR results are shown for late passage cell lines; a similar profile was detected in early passage cells. A 1-kb ladder (A) and cDNA originating in SM-56 cells (B), SV40-56 cells (C), LTR-9 cells (D), pStro1+ nonimmortalized cells (E), and plasmid control (F) are shown. The expected band of 748 bp was detected in all cell lines.