Fig. 4.
pMadMAPK is distributed asymmetrically in vivo in Drosophila. A rabbit polyclonal antibody reagent specific for Drosophila Mad phosphorylated by MAPK at its unique PXSP site was developed (see Materials and Methods). (A) High power view of Drosophila embryos at the cellular blastoderm stage stained with pMadMAPK antibody. (B) Same field co-stained for γ-tubulin (red) and pMadMAPK(green). (C) Triple staining including the DNA stain DAPI (gray). Note that each Drosophila blastoderm cell contains a single asymmetrical spot of accumulation of pMadMAPK antigen adjacent or nearby one of the two centrosomes marked by γ-tubulin (we note that in few cells the intensity is lower). For low-power views see Fig. S4. (Scale bar: 2 μm.)