Uding C. elegans and humans [39,40]. What is the function of the Roc2-Cul5 complex in vivo? A previous Drosophila study used viable P element insertions in the 59UTR of Cul5 for over-expression experiments that suggested Cul5 is involved in cell fate specification and bouton formation in the larval CNS [41]. This study indicated that the insertion alleles were very weakly hypomorphic, and consiste