3.7kb HindIII HpaII fragment of the sc promoter, from position 37.2 to 33.5 on the AS-C map, drives expression of lacZ. HpaII site at coordinate 33.5 is located within the sc leader sequence, 31 nucleotides upstream of the coding sequence.
In third instar wing disc, expressed in pattern of spots or patches corresponding to proneural clusters that give rise to various wing sensilla; most conspicuous are the tsm (twin sensilla of margin 1) and L3 (sensilla campaniformia of dorsal radius) regions.
Expression is similar to that of endogenous sc, and is observed in sensory mother cells and but not in the associated clusters of the wing disc, except for the dorsocentral and supralar macrochaete precursors, for which expression is observed in the associated proneural clusters. Strong expression is also observed in five patches on the wing primordium, covering an area much larger than that of endogenous sc.