Mutants of the "dek1" gene block the formation of aleurone and cause the cells to develop as starchy endosperm cells instead of aleurone cells. This causes the seed to lack an aleurone layer. This mutation is caused by the insertion of a "Mu" transposon into the "dek1" gene, causing it to function incorrectly. However, this transposon may sometimes remove itself from the gene, restoring the function of "dek1". Experiments in this area have helped demonstrate that the cues that determine aleurone positioning are still present in the later stages of development, and the aleurone cells still respond to these cues.