Figure 2

Suspension culture promotes differentiation of normal laryngeal cells but not HPV-infected papilloma cells. A: Normal or laryngeal papilloma cells were cultured in suspension. At indicated times, cells were harvested and keratin extracts were prepared and analyzed by Western blot, as described in Materials and Methods. Figures are representative of 2 separate experiments. B: Normal cells cultured on plastic. C: Quantitative analysis of K13/K14 expression. Results represent mean ± SD from 2 independent duplicate experiments. The relative K13/K14 ratio was set to 1 at 0 h in each group. The K13/K14 ratio showed that normal laryngeal cells were significantly induced to differentiate at 24 and 48 h by suspension culture (*P < 0.01), whereas papilloma cells in suspension culture and normal cells cultured on plastic were not (P > 0.05). P values were evaluated by Student’s t-test.