FIGURE 5.

MAPK-induced nuclear/cytoplasmic shuttling of ARE binding proteins. (A) DDT1-MF2 cells were transiently transfected with HuR-eYFP. Anisomycin was added to the cells to stimulate nuclear to cytoplasmic shuttling. A single cell was tracked for the time course indicated. eYFP-labeled HuR rapidly shuttles from the nucleus to the cytoplasm. Cells were maintained at 37°C, 5% CO₂ for the duration of the experiment. (B) Following treatment with anisomycin (1–24 h), DDT1-MF2 cells were harvested and nuclear and cytosolic fractions isolated. Immunodetection of endogenous AUF1 (p37, p40, p42, p45) and HuR was performed by Western blotting. For normalization, blots were stripped and reprobed for actin protein.