Characterization of Drosophila CP110 and generation of a CP110 null mutant. (A) A schematic representation of the Drosophila CP110 gene (green), its three protein isoforms (blue—note that CP110S1 and CP110S2 differ by only 2aa’s—yellow box), and the two annotated human CP110 isoforms (purple). The region of CP110 used for antibody production is highlighted, and the positions of the P-elements, used to generate the CP110Δ deletion, are indicated by black arrowheads (see Fig. S1 for more detail). The two conserved regions are boxed (CR1, orange boxes; CR2, red boxes). (B) Panels show Western blots of Drosophila syncytial embryos, third instar larval wing discs or brains, or pupal testes or antennae from WT, CP110Δ, or either Ubq-CP110L-GFP– or Ubq-CP110S-GFP–expressing lines probed with α-CP110 antibody or α-actin antibody (loading control). Endogenous CP110L (L) is expressed in embryos, wing disc, and brain cells and is missing in CP110Δ tissues. Endogenous CP110S (S) is expressed in testes and antennae and is also missing in the CP110Δ tissue, although this is partially obscured by a co-migrating background band (S*). A serial dilution of the embryo extract overexpressing CP110L-GFP is shown to illustrate how we estimated levels of overexpression. (C) Neuroblasts from WT and CP110Δ third instar larvae were stained for CP110 (green), Asl (red), Cnn (blue), and DNA (Hoechst; white in merge). Bars, 5 µm.