Figure 3. PIP2 retains its colocalization with UBF during mitosis as demonstrated by near-native IEM. Immunogold electron microscopy of the cryo-immobilized and freeze-substituted mitotic cells demonstrates in ultrastructural detail that PIP2 colocalizes with UBF in discernible NORs (marked by arrowheads). PIP2 occupies the whole NOR volume rather than being sequestered in distinct sub-domains. Ch, chromatin; MT, microtubules. Scale bar: 200 nm.