The flow cytometry analysis revealed the existence of distinct sub-populations with differential expression of CD44: a small sub-population of CD44high cells could be identified in both the SCLC cell line LC004 and the LCC cell line LC006, representing 6.63% (Figure 3A) or 2.79% of total cells (Figure 3B), respectively. This evidence concerns the gene CD44 and small cell lung carcinoma.