Fig. 6. SG2 is directly regulated by Fkh and Sage, whereas SG1 is not. (A) Global expression of sage, achieved by driving UAS-sage with a tub-GAL4 driver, resulted in ectopic expression of both SG1 and SG2 in tissues outside the salivary gland, notably in the foregut (fg), hindgut (hg) and Malphigian tubules (mt) (Aa-a'', Ab-b''). (Aa) SG1 was also expressed in two rows of cells in each segment during stage 11 (arrows). (Ac-c'') The tissues that expressed ectopic SG1 and SG2 also express Fkh protein, including faint expression in two rows of cells in each segment during stage 11 (Ac, arrows). (B) Mutations in the bHLH binding sites (Ba-a'') or the bHLH and Fkh-binding sites (Bb-b'') in the SG1 972 enhancer did not affect expression of the lacZ reporter. (C) Mutations in the bHLH binding sites (Ca-a'') or the bHLH and Fkh-binding sites (Cb-b'') in the SG2 885 enhancer resulted in either reduction or complete loss of salivary gland expression of the lacZ reporter, respectively.