Expression of Ktub in Drosophila photoreceptor cells. Drosophila photoreceptor cells were stained with rhodamine-phalloidin and anti-Ktub antibody. When flies were reared under dark conditions, the majority of Ktub appeared in the rhabdomere domain (A’, arrows). The subcellular localization of Ktub is light sensitive. When flies were removed from the dark and immediately dissected in the light, the Ktub became to localize in the cytoplasm of photoreceptor cells (B’). When flies were exposed to light (500 lux) for 12 hours, the majority of Ktub appeared in the nucleus with some in the cytoplasm (C’). A, B and C were stained with rhodamine-phalloidin (red) A’, B’ and C’ were stained with anti-Ktub antibody (green). A”, B” and C” are merged images. The scale bar is 10 μm.