Cyclins are positive regulatory subunits of the cyclin-dependent kinases (CDKs), and thereby play an essential role in the control of the cell cycle, notably via their destruction during cell division. Probably functions redundantly with other cyclins in regulation of cell cycle. Its presence may be required to delay a deadline for completing cytokinesis that is ordinary imposed by nuclear envelope reformation. Degradation of CycB and CycB3 promote cytokinesis furrow initiation and ingression. Required with CycB for female fertility. Interacts with Cdk1 kinase. In embryo, it is expressed in all mitotically proliferating cells, with a high level in neuroblasts. Not expressed in old embryos and thereafter. Not expressed in endoreplicating tissues. Expressed both maternally and zygotically. The N-terminal destruction box (D-box) probably acts as a recognition signal for degradation via the ubiquitin-proteasome pathway. Ubiquitinated (Probable). Ubiquitination leads to its degradation in early anaphase. Belongs to the cyclin family. Cyclin AB subfamily.