FIG. 4.

Identification of the CPEB4 shuttling elements. (A) The CPEB4 internal deletion constructs are depicted. The boxes indicate the parts of the protein that were deleted, and the gray boxes indicate the known functional domains (RNA recognition motifs RRM1 and RRM2 and two zinc fingers [ZF]) of CPEB4. The bar in the N terminus is a myc epitope tag. (B) NIH 3T3 cells were transfected with plasmid DNA encoding the proteins shown in panel A; 12 h later, the cells were treated with LMB for 1 h prior to fixation. Antibody against the myc epitope was used for immunostaining. Exogenous proteins and α-tubulin were monitored by immunoblotting. Size bar = 10 μm. (C) Quantification of the CPEB4 proteins in the nucleus and cytoplasm as described in the legend to Fig. 1. The asterisks refer to statistically significant differences (P < 0.01, Student's t test) between the results for the indicated samples.