UASt regulates expression of Tag:FLAG-tagged aln.
Scer\GAL4aln.Δ/alnUAS.Tag:FLAG rescues alnΔ-Gal4
Scer\GAL4ort.C2/alnUAS.Tag:FLAG rescues aln2
alnUAS.Tag:FLAG/Scer\GAL4CarT.HA fails to rescue aln2