Comparing DEGs within same cluster in lineage traced mice

Hi,

I’m still pretty new to bioinformatics, and still have a lot to learn. We’ve been working on small molecule drugs for cell regeneration, and are using TdTomato (TdT) labeled mice for lineage tracing. We can detect TdT+ cells in our end-state cluster, and want to compare DEGs between the TdT+ and TdT- cells to see how close/far we are from getting mature cells. How would I go about segregating the cells by TdT expression so I can run sc.tl.rank_genes_groups?

Thanks,
René VQ