Figure 9.

NtmybA1 and A2 Have Promoter Activation Abilities in S-Phase–Arrested Cells.

(A) Changes in mitotic index after bombardment. BY2 cells from 8-day-old culture were bombarded with plasmids and cultured in the presence or absence of aphidicolin. Mitotic index was measured at the times indicated after bombardment. Closed triangles, cells cultured with aphidicolin; open triangles, cells cultured without aphidicolin.

(B) Particle bombardment assay. As a reporter plasmid, Catro; CycB1;1 promoter–LUC was used. As effector plasmids, constructs expressing full length NtmybA1 and A2 and Myb domain–VP16 fusions (A1md–VP16 and A2md–VP16) were cobombarded. The bombarded cells were cultured in the presence or absence of aphidicolin for 24 hr, and LUC activity was assayed. As a control, the reporter plasmid was transfected without effector plasmids (Control). All LUC activities are expressed relative to the control (value set to 1). Error bars indicate ±sd. Closed bars, cells cultured with aphidicolin; open bars, cells cultured without aphidicolin.