Taste buds are chemosensory endorgans embedded in the oral epithelium composed of cells that undergo continuous replacement. Mature taste cells live on average 10-14 days and are replaced by new cells when they die. However, the mechanism by which taste cells are produced and integrated into the taste bud as mature taste cells remains unknown. Previous studies approached this issue from either cell cycle gene expression properties or lineage tracing of precursor cells. In our study, we apply a new fate mapping technique that combines these two ideas. This technique, Mosaic Analysis with Double Markers, allows for simultaneous gene knockout and subsequent tracking of single cells. This allows us to study the potency of precursor cells supplying the taste bud while analyzing how gene function regulates the maturation pathway these taste cells take. The following experiments illustrate the initial phase of this investigation.