APP and Alzheimer disease: In the case of the CAT gene, the relative expression level of CAT in AD model flies (elav-Gal4C155/+;+/+;UAS-Aβ42E693G/+ and elav-Gal4C155/+;+/+;UAS-APP.C99-UAS-MAPT/+) was significantly increased to 2.6- and 2.8-fold, respectively, as compared to elav-Gal4C155/+;+/+;+/+ flies (Fig. 5c).