mCul1 overexpression leads to a reduction in SCF function. (A) Moderate overexpression of mCul1 (MS1096/+;UAS-mCul1/+) gives a weak phenotype that sometimes overlaps wild-type. (B) The presence of a deficiency that removes one copy of both dSkpA and dRoc1 (MS1096/T(1;Y)B106;UAS-mCul1/+) strongly enhances the reduction in wing size. (C) Wing with a strong phenotype (MS1096/Y;UAS-mCul1/+). (D) Co-expression of dSkpA (MS1096/Y;UAS-mCul1/UAS-dSkpA) partially restores wing size. (E) Reducing proteasome function by introduction of a dominant negative allele of a proteasome subunit (MS1096/Y;UAS-mCul1/DTS7) enhances the phenotype. (F) Full length Ci level in MS1096 wing disc. (G) Increased level of full length Ci in MS1096/Y;UAS-mCul1/+ wing disc. In F and G, Ci is detected by immunofluorescence. The outline of the posterior part of the disc (that does not express Ci) is shown by the dashed line. The solid line indicates the wing pouch region where GAL4 expression is strongest.