Based on the flow cytometry analysis, we identified three distinctive sub-populations: (i) CD44 + CD24-; (ii) CD44 + CK7 + ; (iii) CK7 + [Supp Fig. 1(A)] for primary lung cancer patients whereas the other hand, CTCs isolated from patients with lung cancer liver metastasis exhibited three distinctive subpopulations: (i) CD44 + CD24 + ; (ii) CD44 + CD24-; and (iii) CD24 + [Supp Fig. 1(B)]. The gene discussed is CD44; the disease is metastasis.