UASt regulatory sequences drive expression of a reporter of N processing by γ-secretase. The reporter consists of the N signal peptide sequence (amino acids 1-60), the N transmembrane domain (amino acids 1710-1891), and a chimeric transcriptional activator (SV) composed of the Su(H) DNA-binding domain (amino acids 109-457) and the Hsim\VP16 transcriptional activation domain (amino acids 2-79). In the absence of γ-secretase, the SV sequence is tethered at the membrane by the N sequence. In the presence of γ-secretase, intramembrane cleavage releases a fragment that includes the SV transcriptional activator, which can translocate to the nucleus and activate N target genes, mimicking increased N pathway activity.