NOTCH activity is restored in cells lacking ICMT by overexpression of RAB8 and in fly wings by constitutively active Rab8^Q67L. (A) Ratios of CSL firefly/CMV renilla in U2OS cells expressing NOTCH1-GFP and cocultured with 3T3 cells expressing J2 for 24 h. 4 d before coculture, the U2OS cells were transfected with either NT or ICMT siRNA and 48 h later, they were transfected with either GFP or GFP-RAB7 as indicated. Values were normalized to the maximum firefly/renilla ratio in NT siRNA–treated GFP-expressing cells. Data plotted are means ± SEM. n = 3. (B) As in A, except the cells were transfected with either GFP or GFP-RAB8. (C) Virgin female Ap-Gal4; UAS-ste14 shRNA flies were crossed to males carrying the indicated Gal4-responsive UAS-Rab transgenes at 29°C. Bar, 1 mm. Below the representative wings, the widths of the bifurcation of L4 and L5 are plotted as percentages of the wing width. Data shown are means ± SEM. n = 10. *, P < 0.05 (two-sided t test).