Fig. 9. N1-ICD directs PCT fates independent of Notch2. (A) Ectopic overexpression of Notch1 intracellular domain is sufficient to promote proximal tubule formation in the absence of -secretase activity. Genotypes are shown to the left of the image. DMSO, vehicle only; DAPT, -secretase inhibitor. (B) Schematic of the proximalization pathway. After RV induction (a Wnt-dependent process), Pax2 and Wt1 begin to separate into distinct expression domains and Lim1 and Dll1 define a distal domain within the RV. However, Notch2 signals are required for separation of proximal from distal fates; in their absence (or when blocked by -secretase inhibitors), only distal tubules form. See text for details. GSI, -secretase inhibitors.