Fig. 3. MVP and VPARP accumulations in the presence of tellurite. (A) Fluorescence micrograph of an untreated HeLa cell stained with an antibody against the major vault protein (LDQN) (red) and counterstained with DAPI. Bar, 10 µm. (B) Pronounced MVP aggregates (arrows) are revealed when HeLa cells are grown at 37°C for 30 min in the presence of 0.5 mmol l^–1 K₂TeO₃. (C) The formation of MVP aggregates is temperature dependent. HeLa cells were cultured at 37°C and then incubated in the presence (filled bars) and absence (open bars) of 0.5 mmol l^–1 K₂TeO₃ for 30 min at the temperatures shown. The number of cells with MVP aggregates (approximately 2 µm or larger) were counted and expressed as a percentage of the total cells. At least 100 cells were examined at each temperature and the experiment was done in triplicate. Values are reported as mean % ± s.d. (D) The percentage of cells with MVP aggregates increases over a 1 h incubation. HeLa cells were incubated in the presence of 0.5 mmol l^–1 K₂TeO₃ for 30 min and the percent of cells with aggregates were quantified as described above. (E) Nearly 20% of the HeLa cells incubated in 5 mmol l^–1 K₂TeO₃ will form MVP aggregates. The higher the concentration of K₂TeO₃, the greater the percentage of HeLa cells with MVP aggregates. (F) Fluorescence micrograph of untreated HeLa cells stained with an antibody against the vault-associated poly(ADP-ribosyl)polymerase (VPARP) and counterstained with DAPI. Bar, 10 µm. (G) VPARP accumulations also appear at the cell periphery during a 30 min incubation in the presence of 0.5 mmol l^–1 K₂TeO₃.