Fig. 9. pRb and Mcm proteins are not present at the same nuclear sites within intact cells. An aliquot of the same CldU-labeled WI38 asynchronous cell culture was stained with anti-pRb, anti-Mcm7 and anti-BrdU antibodies as described in Fig. 7 without a prior Triton X100 extraction. Cells were categorized according to the type of CldU replication pattern. Images corresponding to double- and triple-labeling protocols were pseudocolored as indicated within each panel. Sites that co-localize appear yellow for red/green, light blue or blue-green for blue/green, and magenta for blue/red merged images, respectively. Note the presence of Mcm proteins throughout the nucleus at all cell cycle stages.