FIG. 4.

Tungsten does not increase 66Cl4 proliferation or invasion in vitro. A, 66Cl4 growth was monitored over 10 days while cultured in a range of low-dose tungsten concentrations (0.25–4 ppb). Graph shows cell number (log 10) verses day for each concentration evaluated. B, 66Cl4 invasion assay through a matrigel matrix. 66Cl4 were cultured under control conditions or exposed to 4 or 15 ppb tungsten (W) for 4 weeks. Treatment with 5 ng/ml TGFβ for 96 h was used as a positive control. Graph shows the mean number of cells invaded ±SE for each group, after normalization to control. For control and tungsten-exposed groups, data represent 5 replicate wells from 2 independent experiments. For TGFβ group, data represent 3 replicate wells.