In vertebrates, PCP signaling is evident in the alignment of hair follicles and stereocilia in the inner ear, and required for limb growth. Non-canonical Wnt signaling also regulates directional cell migration and intercalation during convergence and extension during vertebrate gastrulation and kidney development and aberrant PCP signaling thus can lead to severe birth defects. In Drosophila, PCP signaling controls cell fates and orientation of ommatidia in the facet eye as well as the formation and orientation wing hairs. A set of core PCP factors including the transmembrane proteins Fz, Flamingo, Van-Gogh, the adaptor proteins Dishevelled, and Prickle are required for PCP establishment in all tissues. Their interplay during PCP establishment leads to their asymmetric localization within cells with Fz and Dsh localizing to the distal and Vang and Pk localizing to Ribavirin opposite proximal vertex of hexagonal wing cells. These asymmetries are thought to act as cues interpreted by downstream effector genes for the establishment of polarity dependent structures. In particular, each wing cell initiates the growth of a single trichome, an actin and tubulin rich wing hair at the distal vertex at around 30 hrs after puparium formation. About 17 hrs later, the trichome has developed into a cuticle ensheathed, rose-thorn shaped spike filled with a highly organized actin and microtubule fibers that points towards the distal wing tip. In core PCP mutants, a wing hair typically forms in the center of a cell and shows aberrant polarity. Planar cell polarity effector genes, such as inturned, fuzzy, and fritz, act downstream of the core PCP genes. In contrast to core PCP mutants, in PPE mutant wings, an average of two independent trichomes are Tyrphostin AG 879 initiated at various positions in the apical periphery of a wing cell phenotype). A distinct phenotype with four hairs per cell is seen in multiple wing hair mutants, some of which appear to be smaller secondary hairs splitting from larger ones.Epistasis analyses and colocalization studies suggest that a complex of In, Frtz, and Fy localizes to proximal, apical cell vertices in a core PCP gene dependent manner and prevents local hair initiation and/or promotes distal hair initiation.