They showed that a small subpopulation of cells (as few as 100 cells) with the CD44+/CD24−/lin− phenotype was able to produce tumors with similar heterogeneity to that of the original tumor in immunodeficient mice, while other tumor cells, even with as many as 105 to 106 cells, were unable to produce tumors in mice of the same type. This evidence concerns the gene CD44 and neoplasm.