Analysis of Drosophila eye-colour mutations has made seminal contribut
ions to the fields of genetics and biochemistry. Recent findings sugge
st that a subset of eye-colour genes is crucial for vesicular transpor
t of proteins to pigment grannies, specialized lysosomes of eye-pigmen
t cells. Thus, classical work describing more than 85 eye-colour mutat
ions and their genetic interactions offers a remarkable, untapped reso
urce for the genetic analysis of protein delivery to lysosomes.