Fig. 3. G2-M arrest precedes apoptosis in SAOS-2 and U-2OS osteosarcomas. Graphs of 4N DNA content versus Sub-2N DNA content in SAOS-2 (A) and U-20S (B). Tumor cells were infected at 50, 100, 200, and 500 MOI of dnPLK Ad and processed for FACS analysis at 24, 48, and 72 h to determine DNA content. Apoptosis was calculated from percentage of Sub-2N DNA content. 4N DNA contents in control adenovirus populations were 34% for SAOS-2 and 38% for U-20S (single point ).