Association of SINE1 with F-actin filaments in guard cells. (A) GFP-SINE1 is colocalized with rhodamine-phalloidin–labeled filaments in A. thaliana guard cells (arrowheads). (B) The SINE1 fibers in both guard cells and root cells are sensitive to 1-h treatment of 10 µM LatB, but the fibers (arrowheads) are still visible in the mock treatment. The images of guard cells are maximum intensity projections of a z-stack image. The differentiated root cell nuclei were imaged at the nuclear surface. (C) FRAP recovery curves of GFP-SINE1 with or without LatB-triggered F-actin depolymerization. A. thaliana lines stably transformed with GFP-SINE1 driven by the 35S promoter were used for FRAP. The asterisk indicates a significant statistical difference of the maximum recovery compared with the black curve (two-tailed t test, P < 0.01, n = 35). Error bars represent SEMs. Bars, 5 µm.