SKIC2 and retinal degeneration: It was already reported that constant illumination causes retinal degeneration and malfunction in Drosophila w− mutants (Shoup, 1966; Wu and Wong, 1977; Schraermeyer and Dohms, 1993; Lee and Montell, 2004; Bulgakova et al., 2010; Belušič, 2011).