Fig. 2. p42^POP is a widely produced nuclear protein with functional NLS and NES. (A) Expression pattern of p42^POP obtained by quantitative PCR and subsequent Southern-blot analysis with standardized samples. p42^POP is produced in all adult mouse tissues tested, with high expression levels in brain and testis, and is already present at embryonic stage E7. (B,C) Subcellular localization of BiPro-tagged p42^POP (B) and POP6 (C) in PtK2 cells transfected with the appropriate constructs, as revealed by immunofluorescence with anti-BiPro antibody. (D) Compiled data for all constructs tested in analogous assays, using either BiPro- or GFP-tagged probes. Both sets of experiments gave identical results. Whereas p42^POP was seen exclusively in the nucleus, deletion of the C-terminal NLS resulted in an exclusively cytoplasmic location of the appropriate fragments POP6 and POP9. Bar, 10 µm.