Interaction between Ipk2 and JAK/STAT. (A) Ipk2, but not Ipk1, is required for JAK/STAT-mediated transcription. Kc167 cells were treated with dsRNA targeted against Dome, Ipk2, and Ipk1 and assayed using a STAT transcriptional reporter. Relative luciferase units are plotted (mean ± SEM). (B) Ipk2 knockdown causes a reduction in secreted Upd. Cells were transfected with combinations of Upd plasmid, atIpk2-GFP plasmid, and treated with Ipk2 dsRNA, as indicated by the + and – signs. Protein extracts and conditioned medium were immunoblotted with antibodies against Upd, Ipk2, GFP, or actin. (C and D) ipk2 suppresses the eye overproliferation phenotype caused by ectopic expression of Upd. (C) Shown are representative images of heads from pharate adults of the genotypes indicated below the images. (D) Mean eye sizes of the genotypes indicated in C (mean ± SEM, n ≥ 6). (E and F) hopTum-l partially rescues the small wing phenotype of ipk2. (E) Representative images of pupal wings of the indicated genotypes. (F) Mean pupal wing sizes of these flies (mean ± SEM, n ≥ 40).