Fig. 6. Rescue of the mbt eye phenotype by transgenic constructs. Tangential sections of eyes of the following genotypes: (A) mbt^P1/Y; UAS:mbt/+; Gal4:238Y/+; (B) mbt^P1/Y; UAS:mbt^T525A/+; Gal4:238Y/+; and (C) mbt^P1/Y; UAS:mbt^H19,22L/+; Gal4:238Y/+. Expression of the mbt cDNA with Gal4 line 238Y in a mbt^P1 mutant background results in a complete rescue of the mbt^P1 eye phenotype (A, compare with Fig. 1B). Mbt^T525A can only partially substitute the loss of endogenous Mbt function (B); occasionally photoreceptor cells are missing (arrows). No rescue of the mbt^P1 phenotype is observed upon expression of the mbt^H19,22L construct (C). Scale bar: 10 µm.