Fig. 3. GAL4 activation of the Fbp1 EcRU is dependent upon the integrity of at least one of the two GBS1 or GBS3 sites. Late third instar larval tissues from transgenic lines with the indicated genotypes (right-hand side) were histochemically stained for ß-galactosidase activity. Structures of the constructs in transgenic lines (left-hand side) are depicted as in Fig. 2. Expression of the AE[UAS2-3] reporter construct in either the absence (A) or the presence (B) of the GAL4^daG32 driver is shown.