Fig. 4. Exogenous CHMP1 blocks cell-cycle progression in late S-phase. IND-CHMP1 cells were induced with 10 µM muristerone for the indicated times. (A) Cells were scored for exogenous CHMP1 expression (triangles) and histone H3 phosphorylation (Ser10) with specific antibodies (see Methods). The phospho-H3 (P-H3) pattern was scored as punctate nuclear (open squares), or uniform nuclear and therefore mitotic (closed squares). DNA replication was measured by BrdU incorporation (asterisk) and apoptosis by TUNEL labeling (open circles). (B) The IND-CHMP1 line and its parental activator line (Invitrogen) were induced with muristerone for the indicated times, fixed, stained with propidium iodide and analyzed by flow sorting. The percentage of cells in each cycle phase is indicated in the corner of each panel.