HOXA9 and central nervous system cancer: Strikingly, we also showed that hTERT/E6/E7 immortalized astrocytes that overexpress HOXA9 are able to originate orthotopic gliomas in vivo, in contrast to HOXA9-negative hTERT/E6/E7 cells (Figure 5), which may partly be explained by the notion that tumor-initiating cells have high stem cell potential.