As of now, OS research has progressed exclusively through a series of analyses combining cell lineage-specific conventional cre mouse lines and floxed mice carrying cancer-related genes, mainly p53. However, the identification of the genuine cells of origin for OS is difficult because the conventional cre system continuously deletes target genes in a variety of cells, starting at the embryonic stage and continuing through all other life stages. The gene discussed is TP53; the disease is cancer.