The acquisition of cellular adhesion machinery likely represented a key factor in the evolutionary transition from unicellular to multicellular organisms. Within metazoa, cellular adhesion is an integral aspect of organismal integrity through its regulation of a wide range of processes, including tissue patterning, cellular proliferation, and migration. As such, dysregulation of adhesion has been linked to diverse pathologies including cancers and neurodegenerative diseases. At the molecular level, adhesion is mediated by specific transmembrane cell adhesion molecules (CAMs) and intracellular complexes that create a dynamic link between the extracellular milieu and the intracellular cytoskeleton. At the sequence level, immunoglobulin domains act to mediate homo- and heterophilic interactions among CAMs and thus adhesion between neighboring cells. LIGs, a family of Ig-containing proteins that contain Leucine-rich repeats, represent candidates for novel CAMs with functions in axonal regeneration and synaptic pathfinding - all of which are highly dependent on cellular adhesion. In Drosophila, two LIG family members, Kekkon1 (Kek1) and Kekkon5 (Kek5) have been been implicated in EGF signaling, and Bone Morphogenetic Protein signaling as well as cellular adhesion, respectively. To investigate the putative role of Kek5 as a CAM, characterization of Kek5 activity was carried out at the cellular and molecular level. From this it was discovered that Kek5 is able to induce a dramatic upregulation of the adherens junction component Armadillo, in addition to epithelial extrusion and cell enlargement. Together, the studies presented within support a model in which Kek5 acts in a homophilic fashion to upregulate Arm and that this activity is functionally separable from other observed effects (epithelial extrusion and cell enlargement).