Cao et al. BMC Cancer 2010, 10:68 http://www.biomedcentral.com/1471-2407/10/68 Page 9 of 11 Figure 4 Northern blotting analysis of SSH data. Conditioned culture CNE-2 single clone cells show detectable higher mRNA transcription of ARMER (A), PCBP1 (B), PDHB (C) and FUBI (D) compared with control. The ethidium bromide-stained 28S/18S rRNA bands were used as a control for loading variation. membrane of the endoplasmic reticulum [31], and was one of the most intensely up-regulated gene when cul- tured with the differentiated THP-1 conditioned media. Figure 3 reveals a large amount of apoptotic cells in the control and proportionally less in the conditioned cul- ture population. Thus, the possible anti-apoptotic effect of ARMER may be induced when cultured with the con- ditioned medium. While PCBP1 plays a role in the pro- tein-protein interaction network for human inherited ataxias and disorders of Purkinje cell degeneration [32]. PDHB is involved in tricarboxylic acid cycle of fibroblast [33]. We also found that FUBI mRNA transcript level was increased in conditioned cultured cells compared with control. Overexpression of FUBI leads to cell death, which can be halted by Bcl-2 or inhibition of cas- pases [29,34]. We have tried to compare our gene pro- file data with those of similar study on hepatocellular carcinoma, thyroid cancer and lung adenocarcinoma, but they are not in the same pattern suggesting the het- erogenic nature of different malignancies. None of the up-regulated genes in non-SP cells found here have been documented to be involved in NPC. This might be partly explained by the different characteristics of non- SP cells and SP cells. The abundance of SP in CSCs from the same tumor contributes to distinct gene expression patterns, which has been often neglected by previous studies for many years. Conclusion We have identified, for the first time, non-SP single clone cells can generate SP phenotype when they are cultured with macrophage-like cells. It should be noted that non-SP single clone cells derived directly from NPC CNE-2 cells would like to maintain non-SP characters, whereas non-SP cells sorted with FACS were inclined to gain SP. The underneath mechanism of the interesting phenomena is far yet clear. Further studies are needed to further pin-point the original source of the cancer stem cell in NPC and apply it for establishment a novel therapy of this malignancy.