Figure 5. Cr(VI) induces phosphorylation of STAT3 in the nucleus.

Immunofluorescence confocal microscopy was used to confirm that Cr(VI) increases nuclear levels of phosphorylated STAT3. BEAS 2B cells grown on coverslips or pHBE cells grown on transwell membranes in air/liquid interface cultures were exposed to 5 μM Cr(VI) (72 h) or to 0.01 μg/ml of IL-6 (30 min). Following fixation and permeabilization, cells were immunostained with antibodies against either pY-STAT3 or total STAT3 (green), as described in the Materials and methods section. (B, D) These Figures show (A) and (C) merged with images of the nuclei stained with TO-PRO3 (blue). These results were from three independent experiments performed in duplicate.