first cyclin box found in cyclin-B1 (CCNB1)-like family
The CCNB1-like family includes two B-type cyclins, CCNB1 and CCNB2, both of which are essential for the control of the cell cycle at the G2/M (mitosis) transition. Members in this family contain two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.