sentence: The results presented here identify CDKA ;3 as such a candidate CDK and underscore potentially important differences in cell cycle control resulting from higher A-type CDK complexity in species like maize , in comparison to species containing a single A-type CDK , such as Arabidopsis thaliana.A positive role for maize CDKB1 ; 1 in the mitotic cell cycle is likewise supported by the effects caused by reduced RBR1 expression in RBR1DS1 endosperm , in which CDKB1 ; 1 expression was increased ( Fig. 4 ) .