Table 1. Morphometric analysis.

Cell line	Stress fibers per cell	N/C ratio
C-33A	3 ± 1	0.6
SiHa	13 ± 3	0.28
CaSki	20 ± 4	0.26

Morphometric evaluation of two structural cell parameters - number of stress fibers and nucleus/cytoplasm ratio - in three different carcinoma cell lines that express different levels of HPV and E7 DNA: null (C-33A), low (SiHa) or high (CaSki). Of note, significant differences were appreciated between HPV16-null cells and cells with a different number of copies of HPV16 DNA, which show a higher content of polymeric actin stress fibers and also display a larger cytoplasm.