Fig. 4. Density-dependent protein stabilisation of hDlg in epithelial cells. HPV-16-positive CaSKi, HPV-18-positive HeLa, plus HPV-negative HaCaT and C33I cells were grown to 25% (L), 50% (M) or 75% (H) confluence and then either treated (+) or not (–) with the proteasome inhibitor CBZ for four hours prior to cell extraction. Western blot was then performed to analyse hDlg protein levels.