Fig 4.

16E5 levels in immortalized and transformed cervical cell lines. (A) Real-time PCR showing levels of E5 and E1^E4 transcripts relative to GAPDH in HPV-16-negative (C33A) and HPV-16-positive (SiHa and Caski) cervical cancer cell lines. Error bars represent means ± standard errors of the means (SEM) (n = 3). (B) Chromatograms of D5-FLIT/FLIT transitions for the deuterated internal standard added to tryptic digests of the cervical cancer cell lines in panel A and for HPV-16 E6/E7-immortalized HECs that stably express wt 16E5. (C) Chromatograms of FLIT/IT transitions for endogenous FLIT peptide in the tryptic digests. No endogenous FLIT was detected in C33A and SiHa cells. All retention times of the deuterated internal standards and endogenous FLIT were 25.08 ± 0.4 min (15-cm column).