Fig. 5.

16E1^E4-keratin association results in the observation of high molecular weight K8-K18 ladders, which accumulate upon proteasomal inhibition. (A) SiHa cells were infected to express 16E1^E4, ΔLLKLL, or β-Gal and harvested 12, 24 or 48 hours after infection. Western blots were probed to detect proteins as indicated on the right, both high and low exposures of K8 and K18 blots are shown (bold); GAPDH was used as a loading control. In the high-exposure blots, accumulation of high molecular weight K8 and K18 ladders is evident only in cells expressing 16E1^E4. (B) SiHa cells, infected to express 16E1^E4 or β-Gal, were treated with the proteasomal inhibitor ALLN 18 hours before harvest. Accumulation of high molecular weight K18 species on proteasomal inhibition indicates that they are ubiquitylated.