The amount of total H3, H34K4me3, H3K4me2 and H3K4me1 associated with the transcription start site present in the HPV18 LCR (A) or HPV18 L1 ORF (B) was determined in HeLa/16E6/16E7/BE2 or HeLa/16E6/16E7/pOZN cells by ChIP. The fold change displayed on the y-axis represents data normalized to the β-actin transcriptional start site, with each bar representing the average of three experiments ± SD. HeLa/16E6/16E7/BE2 (C, E) or HeLa/16E6/16E7/pOZN cells (D, F) were transfected with the indicated siRNAs (legend in C). 72 h post-transfection, the amount of total H3, H34K4me3, H3K4me2 and H3K4me1 associated with the HPV18 LCR (C, D) or L1 ORF (E, F) was determined by ChIP. The fold change displayed on the y-axis represents data normalized to the β-actin transcriptional start site, with each bar representing the average of two experiments ± the difference between them. Asterisks represent the level of significance (* p-value ≤ 0.05 and ** p-value ≤ 0.005), as determined via unpaired t-tests.