Fig. 2. Kra is expressed in the embryonic CNS. (A) Western blot analysis of S2 cell extracts using anti-Kra. The recognized protein is significantly depleted in kra RNAi-treated cells but not in gfp RNAi-treated control cells. (B-D) Whole-mount wild-type embryos stained with anti-Kra. Brackets mark the ventral nerve cord (VNC). (B) A stage 3 embryo. Lateral view. (C) A stage 13 embryo. Lateral view. (D) A stage 16 embryo. Ventral view. (E) A stage 16 embryo stained with preimmune serum. Ventral view. (F-H) A confocal section (1 µm) of a stage 16 wild-type embryo labeled with anti-Kra (F) and anti-Elav (G). (H) Merge of F and G. (I-K) A confocal section (1 µm) of a stage 16 wild-type embryo labeled with anti-Kra (I) and anti-Repo (J). (K) Merge of I and J. (I'-K') Higher magnification of the area marked with white broken lines in I-K. (L) The CNS of embryos, carrying both ap-GAL4 and UAS-HA-Kra^WT, stained with anti-HA. HA-Kra protein is detected in both the bodies (arrow) and the axons (arrowhead) of the Ap neurons. Scale bars: in F, 10 µm for F-L; in I', 10 µm for I'-K'.