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Fig. 5. The replication fork proteins RPA and PCNA, but not nuclear lamins,
colocalize with BrdU-labeled nascent DNA within replication foci. HeLa and
WI38 cells were pulse-labeled with BrdU, extracted with Triton X100 to remove
soluble proteins and fixed with freshly prepared formaldehyde. (A-C) One
aliquot of the cells was treated with HCl and then stained simultaneously with
lamin B- (green) and BrdU-specific (red) antibodies. A second aliquot was
first stained for lamin B [green (D-G)] or lamin A/C [red (J-Q)], the cells
were fixed again with formaldehyde, then treated with HCl and stained for BrdU
(red in D-F and green in J-Q). (H) The same protocol was used to stain for
PCNA (red) and BrdU (green). (I) A fourth aliquot of cells was stained
directly with anti-PCNA (red) and anti-RPA (green) antibodies. Results
obtained with HeLa cells are shown in panels A-I. Identical results were
obtained with WI38 cells.