Figure 4. Bortezomib-induced cell death is modestly dependent on p53 in HPV-positive cells, but independent of p53 in HPV-negative cells. HPV-negative (top panels) and HPV-positive (bottom panels) HNSCC cells were transfected with 100 nM nonspecific siRNA or p53 siRNA. Twenty-four h after transfection, cells were treated for 48 h with varying concentrations of bortezomib, followed by assessment of cell viabilities by trypan blue exclusion. Error bars represent the standard deviations of triplicate wells. The experiment was performed three times with similar results.