Fig. 6. Expression of GW182 in HeLa cells synchronized by double thymidine block. (A) Cells were processed for IIF at 0, 3, 6 and 9 hours after release from thymidine block and stained with human anti-PCNA serum or the index human anti-GW182 serum. At 0 and 3 hours, most cells stained with anti-PCNA showed the fine nuclear speckled distribution (arrowheads) characteristic of cells in early and mid S phase. Most cells had small GWBs. At 6 and 9 hours, apparently larger GWBs (long arrows) were observed along with the characteristic nucleolar distribution of PCNA in late S and G2 phase (arrows). Scale bar; 10 µm. (B) Western blot analysis of GW182 showed increased expression from early S phase (0 hour), mid S (3 hours), late S (6 hours) to G2 phase (9 hours). Furthermore, slower migrating, diffuse bands (arrowhead) were observed at the later stages suggestive of post-translational modifications, such as phosphorylation.