The effect of HPV oncogenes on the level of IVL protein in HFK cells. Generation of cell lines and induction of differentiation was performed as described in the legend to Figure 1. Ten μg of protein extracts prepared from the indicated cell lines were subjected to Western blot analysis for IVL or actin protein (the latter as loading control). (A) Parts of representative X-ray films are shown. (B) The amount of IVL protein was quantitatively analyzed by densitometry and standardized to actin protein level. The standardized density value of cycling cells transduced by LXSN was set to 1, and other values are shown relative to this. Values show the means from four independent experiments with standard errors shown as error bars.