FIG. 5.

Pnn is not a nucleocytoplasmic shuttle protein. (A to C) Heterokaryons were formed between canine MDCK cells and mouse NIH 3T3 cells, followed by immunostaining with polyclonal anti-Pnn antibodies. (D to G) HeLa cells were cotransfected with vectors for myc-tagged canine Pnn and control protein GFP-hnRNPA1 and subsequently fused with NIH 3T3 cells after transfection for 36 h. Transiently expressed Pnn was immunofluorescently detected by monoclonal anti-myc antibody (D). The cells were stained with Hoechst 33258 to distinguish mouse (arrow) from canine (B) or human (F) nuclei. Panels C and G show cells visualized by phase-contrast microscopy.