Fig. 2. Eye pigmentation in presence or absence of the bxd PRE. (A) Eye pigmentation is repressed by the PRE in line 8 (left) and is increased by deleting the PRE (right). (B) PRE repression is decreased by a heterozygous Pc mutation (right) compared to the wild type (left). (C) In line 91, eye pigmentation is stronger in presence of the PRE (left) than in its absence (right). (D) The stimulating effect of the PRE is due to TRX. In flies heterozygous for a trx mutation, eye pigmentation decreases (left) to a level comparable to lines without the PRE (right). Eye pigmentation in absence of the PRE is much stronger in line 91 compared to line 8 (compare A, C, right).