Fig. 4.

The GCCCR element is necessary and sufficient to confer high-level CYCB1;1 expression in mitosis. Oligonucleotides with the MSA element or the GCCCR element were cloned 5′ of the minimal 35S-46 promoter. The minimal promoter is not cell cycle phase-regulated, but addition of the MSA element restores expression at G₂/M. Addition of the GCCCR element alone slightly suppresses expression directed by the minimal promoter. However, addition of the GCCCR element to the MSA element strongly enhances expression with appropriate timing at G₂/M.