FIG. 3.

Depletion of either SAP145 or SAP49 induces G₂ cell cycle arrest. (A) The cell cycle profiles of GFP- (control), wild-type GFP-Vpr-, or GFP-Vpr-ΔC-transfected HeLa cells were analyzed by FACS at 48 h after transfection (top). Cell cycle phenotypes of SAP145- or SAP49-depleted cells (bottom). HeLa cells with or without stably expressed HA-tagged SAP49 were transfected with either luciferase siRNA (control) or SAP145- and SAP49-specific siRNAs. The cell cycle distribution was analyzed by FACS 48 h after transfection. The G₁, S, and the G₂/M phases are indicated. (B) Immunoblot analysis with whole-cell lysates from HeLa cells transfected for 0, 24, 48, or 72 with either SAP145 or SAP49 siRNAs. Blots were probed with anti-cdc2, anti-SAP145, or anti-HA (SAP49) antibodies. (N) sample from nocodazole-synchronized cells. The positions of hypo- and hyperphosphorylated cdc2 are indicated.