The present invention relates to the isolation and identification of a nucleic acid molecule which regulates fruit size and/or cell division in plants and the protein encoded by such a nucleic acid molecule. The invention also relates to an expression vector containing the encoding nucleic acid and methods whereby fruit size is reduced and/or increased and cell division is regulated by transformation of plants with the disclosed nucleic acid molecule. Host cells as well as transgenic plants and plant seeds containing the nucleic acid molecule of the present invention are also discussed.