Only a few markers such as CD56 (N-CAM, neural cell adhesion molecule 1 isoform, a hallmark of SCLC), CD90 (Thy-1, a neuronal and mesenchymal stem cell marker), CXCR4 (metastasis-associated G-protein receptor) and CD44 (associated with breast and other CSCs) were expressed in all cell lines, whereas expression of CD133, associated with cancer stem cells in many other tumour types (Mizrak et al, 2008), including non-small-cell lung cancer (Eramo et al, 2008), varied from nearly 100% positive in H82 to 20% in H146 and was non-detectable in H526 cells. This evidence concerns the gene CXCR4 and small cell lung carcinoma.