Has a dual function as a transcriptional activator and a repressor of the hedgehog (Hh) pathway. The full-length ci form (ciFL), acts as an activator (ciA) while ciR, its C-terminally truncated form, acts as a repressor. Involved in segment polarity. Required for the normal development of the posterior half of each embryonic segment. Engrailed protein directly represses ci expression in posterior compartment cells. Essential component of a hh-signaling pathway which regulates the Duox-dependent gut immune response to bacterial uracil; required to activate Cad99C-dependent endosome formation, norpA-dependent Ca2+ mobilization and p38 MAPK, which are essential steps in the Duox-dependent production of reactive oxygen species (ROS) in response to intestinal bacterial infection (PubMed:25639794). Interacts with RDX (PubMed:16740475). Interacts with cos (PubMed:9244298, PubMed:15691767). Interacts with slmb; the interaction is enhanced by phosphorylation by CkIalpha and dco (PubMed:16326393). In embryos, expressed uniformly throughout the blastoderm stage and gastrulation (from stage 5). During stage 10, ci is eliminated from the posterior compartment of each segment forming 15 segmentally repeating stripes at the end of the short phase of germ-band extension. Polyubiquitinated by RDX in the presence of CUL3, which results in proteasomal degradation. Phosphorylated on multiple sites by protein kinase A (PKA) and phosphorylation by PKA primes further phosphorylation by CK1 and GSK3. Phosphorylation is essential for its proteolytic processing. cos recruits multiple kinases to promote efficient phosphorylation of ci while Hh signaling inhibits phosphorylation by restricting the accessibility of ci to the kinases (PubMed:15691767). Phosphorylation by CkIalpha and dco enhances binding to Slmb, the F-box recognition component of the SCF(slmb) E3 ubiquitin-protein ligase required for ci processing (PubMed:16326393). Transcriptional repressor ciR, a C-terminally truncated form, is generated from the full-length ci (ciFL/ci-155) through proteolytic processing. Hh suppresses the formation of ci75 and promotes the conversion of ci155 into a transcriptional activator (ci155A). RNAi-mediated knockdown severely reduces adult survival following the ingestion of E.carotovora. Abolishes Cad99C-dependent formation of endosomes and DUOX-dependent up-regulation of reactive oxygen species (ROS) in the intestines of adults fed bacteria-derived uracil. Belongs to the GLI C2H2-type zinc-finger protein family.