Interacts with FZR2/CCS52A1, FZR1/CCS52A2 and FZR3/CCS52B. Expressed in root tip, lateral root apex, shoot apex, leaf primordia, axillary buds, stamen and petal primordia, ovules and developing embryo. Expressed early in the G2 phase, reaches a peak at mitosis and then decreases. Expressed in the developing embryo up to the late-heart and early-torpedo stages. By auxin and nematode infection in roots. Down-regulated by salt stress in root meristem and shoot apex. Belongs to the cyclin family. Cyclin AB subfamily.