All isoforms are required for patterning of the embryonic cuticle. Acts with exd to delimit the eye field and prevent inappropriate eye development. Isoforms that carry the homeodomain are required for proper localization of chordotonal organs within the peripheral nervous system and antennal identity; required to activate antennal-specific genes, such as sal and to repress the leg-like expression of dac. Necessary for the nuclear localization of the essential HOX cofactor, extradenticle (exd). Both necessary and sufficient for inner photoreceptors to adopt the polarization-sensitive 'dorsal rim area' (DRA) of the eye fate instead of the color-sensitive default state. This occurs by increasing rhabdomere size and uncoupling R7-R8 communication to allow both cells to express the same opsin rather than different ones as required for color vision. Interacts with exd; required for nuclear translocation of exd. In the wing disk, the expression is present in the regions corresponding to notum, wing hinge and ventral pleura. In the leg disk, the expression is in the periphery region, corresponding to the proximal segments of the legs. In the antennal disk, the expression is in all but the arista region. In the eye disk, the expression is strong in the anterior region surrounding the eye field, including the regions corresponding to ptilinum, ocellus and head capsules, and weak in the posterior and lateral margins of the eye disk. Expressed specifically in maturating inner photoreceptors of the DRA and maintained through adulthood. Isoform C, isoform E and isoform F have very similar expression patterns during embryonic and larval stages, suggesting coexpression in the same tissues. Severe head defects, including a failure of head involution and transformation of the thoracic and abdominal segments into a more posterior identity. Protein lacks the homeodomain but is still capable of interacting with exd. Protein lacks the homeodomain but is still capable of interacting with exd. Belongs to the TALE/MEIS homeobox family.