Figure 2

Pre-treatment with thymidine arrests cells in G1 and once removed, allows a synchronous entry into S phase. (A) Thymidine was added at 1 mM (ii) or 0 mM (i) for 24 hours, cells were then harvested and processed for cell cycle analysis, representing the cell cycle profile at the time of oligonucleotide electroporation. (B) Cells were treated for 24 hours as in A, but were washed 2× with PBS at 24 hours and released into fresh media for 8 hours, at which time they were either collected for cell cycle analysis (i and ii) or were stained for BrdU incorporation (iii and iv) to measure their replicative state. The position of M1 (BrdU+ marker) was determined by a BrdU(-) control, not shown, and percents indicate the number of cells that are positive for BrdU in the total sample size (25,000 cells).