These cells show a higher expression of stem-cell marker genes (i.e., cluster of differentiation (CD)34, CD44, CD123, CD133, octamer-binding transcription factor 3⁄4 (Oct3/4), SRY-Box transcription factor 2 (Sox2), Nanog, c-Kit, leukemia inhibitory factor (Lif), adenosine 5′-triphosphate (ATP) binding cassette subfamily G member 2 (ABCG2), aldehyde dehydrogenase (ALDH), and C-X-C motif chemokine receptor 1 (CXCR1)) and contribute to tumor formation as well as progression [15,26,28]. The gene discussed is CD44; the disease is neoplasm.