Fig. 3. Arm expression can activate the transcriptional activity of a moderate loss-of-function allele of arm. arm^XM19 germline clones made using the FLP recombinase system expressing either Arm or S10 using the GAL4/UAS system. (A) Phase contrast images of (arm^XM19; ArmGAL4/+ crossed to Arm) first instar larvae show approx. 25% naked (n=32), approx. 25% wild-type (n=26), approx. 25% arm phenotype (n=27), and approx. 25% naked/arm phenotype (n=35), consistent with arm/+; Arm/ArmGAL4 leading to naked cuticle, arm/+; Arm/+ leading to wild-type cuticle, arm/Y; Arm/+ leading to arm cuticle, and arm/Y; Arm/ArmGAL4 leading to the naked/arm cuticle. (B) Confocal images of embryos (arm^XM19; ArmGAL4/+ crossed to either Arm or S10) showing the En stripes (-En, red). An embryo with wild-type Engrailed stripes is shown for comparison. All panels were also stained with Sxl (not shown) to separate out the arm^XM19/+ embryos.