Table 1. Gal4 Drivers and Markers Used in This Study.

Name of fly lines	Expression patterns	References
Ro-tau-LacZ (rtl)	β-Galactosidase expression in R2–R5 axons	24
Ato-tau-Myc(atm)	Myc protein expression in R8 axon and growth cones	25,26
109.68-Gal4	Gal4 protein expression in R8 cells	17,18
puc-LacZ	β-Galactosidase expression driven by puckered promoter	32
GMR-Gal4	Gal4 expression in the eye	30
Elav-Gal4	Gal4 expression in neurons	31