Fig. 6. Protein stabilization after depletion of Pros26.4. Uniform overexpression of Hairless (red) was induced by a heat shock pulse and detected one hour and 12 hours post-induction, respectively. (A,A') DIAP1 was overexpressed along the antero-posterior boundary of the imaginal disc and detected with anti-DIAP1 antibodies (green). Hairless remains at slightly elevated levels in the DIAP1 expressing cells after 12 hours (arrow). Genotype: UAS-DIAP1 / +, ptc-Gal4/+, hsH / +. (B) The same experiment was performed while depleting Pros26.4 along the antero-posterior boundary by RNAi. Accumulation of Hairless protein along the border is visible already one hour post-induction (arrow). (B') At 12 hours post-induction, stabilization of Hairless is very obvious along the antero-posterior boundary (arrow). Genotype: UAS-DIAP1 / +, ptc-Gal4 / +, UAS-dsS4 hsH / +. (C-D') Su(H) protein expression (red) was induced uniformly by heat shock. (C) A very subtle stabilization along the antero-posterior boundary was observed by DIAP1 overexpression (green) at 1 hour post induction (arrow) which was no longer detectable 12 hours later (C'). (D,D') Simultaneous knock-down of Pros26.4 did not cause any specific Su(H) accumulation. Genotypes: UAS-DIAP1 / +, ptc-Gal4 / +, hsSu(H) / + in C) and UAS-DIAP1 / +, ptc-Gal4 / +, UAS-dsS4 hsSu(H) / + in D. (E–F') Intracellular domain of Notch was induced all over by heat shock. Little effect on the stability of Notch (red) was observed by overexpression of either DIAP1 alone (E,E') or by accompanying knock-down of Pros26.4 (F,F'). Genotypes are UAS-DIAP1 / +, ptc-Gal4 / +, hsN^ICD / + in E and UAS-DIAP1, ptc-Gal4 / +, UAS-dsS4 hsN^ICD / + in F. Expression of the respective proteins was detected by immunostaining with DIAP1 antibodies (green) and Hairless (red, A-B'), Su(H) (red, C-D') and Notch (red, E-F'). Arrows point to antero-posterior boundary where dsS4 and/or DIAP1 were overexpressed.