FIGURE 4.

Cytoplasmic accumulation of hnRNP A1 during hypertonic stress depends on eIF2α phosphorylation. A, WT (S/S) and A/A cells were treated with hypertonic medium for the indicated times, and levels of endogenous hnRNP A1 protein were detected in cytoplasmic, nuclear, and total extracts by Western blotting. B–D, confocal microscopy of S/S and A/A MEFs transfected with wild-type (B and D) or F1 mutant (C) FLAG-tagged hnRNP A1. Cells were cultured in hypertonic medium for 3 h and then processed for immunofluorescence. Nuclei were visualized with DAPI. B and C, localization of the FLAG-tagged protein and tubulin. To evaluate cytoplasmic redistribution of FLAG-tagged hnRNP A1, for each condition >100 FLAG-positive cells were analyzed from two independent experiments. D, localization of FLAG-tagged protein and cleaved caspase 3. Arrowhead shows an untransfected cell positive for cleaved caspase 3. Bars, 20 μm.