Key assembly factor of SCF (SKP1-CUL1-F-box protein) E3 ubiquitin ligase complexes that promotes the exchange of the substrate-recognition F-box subunit in SCF complexes, thereby playing a key role in the cellular repertoire of SCF complexes. Acts as a F-box protein exchange factor. Probably plays a similar role in other cullin-RING E3 ubiquitin ligase complexes (Probable). Lethality in the pupal stage. Accumulation of neddylated Cul3 and stabilization of the Cul3 adapter protein HIB. Enhances protein degradation of Cubitus interruptus (Ci), suggesting that Cul3-RING ligase activity is enhanced in the absence of Cand1. Belongs to the CAND family.