Fig. 2. Immunoelectron microscopic visualisation of PcG protein distribution in sections of paraformaldehyde-fixed SW480 cells, following the EDTA staining procedure. (A) Rabbit anti-HPH1 antibody revealed by goat anti-rabbit secondary antibody conjugated with 12 nm colloidal gold particles; (B) rabbit anti-HPC2 antibody and 12 nm particles; (C) rabbit anti-RING1 and 12 nm particles and (D) rabbit anti-BMI1 and 15 nm particles. Nuclear distribution of PcG proteins frequently occurs on electron-dense RNP-containing fibrils, which are distributed in the nucleoplasm (some fibrils indicated by arrowheads). Condensed chromatin (c) is virtually devoid of signal. Bars, 0.3 µm.