Cover photograph (Copyright © 2003, American Society for Microbiology. All Rights Reserved.): In lesions caused by human papillomaviruses (HPVs), surrogate markers of HPV E7 expression persist in the upper epithelial cell layers where HPV E4 expression occurs. The image shows a section through an HPV2-induced papilloma stained for E4 (green) and for MCM2 (red), an E2F-activated gene stimulated by E7. Cell nuclei are counterstained with DAPI (blue). The onset of vegetative viral genome amplification coincides with the onset of E4 expression but does not persist in the most superficial cell layers where E2F-activated genes are no longer expressed (See related article on page 10186.)