Expression and protein localization pattern of SINE1 and SINE2 in leaves. (A) SINE1 is expressed in guard cells and guard cell mother cells (top, arrowheads), and the protein is localized to fibers in guard cells (bottom, arrows). (B) SINE2 is expressed mainly in epidermal cells and mesophyll cells and weakly in guard cells (circled by a dotted ellipse). The images are maximum intensity projections of a z-stack image. Autofluorescence of chloroplasts are shown in red and overlaid with the GFP signal. Bars, 10 µm. In the overlay images, asterisks indicate the nuclei observed, and P letters indicate stomatal pores enclosed by pairs of guard cells.