OLIG2 and neoplasm: Bao et al. (2008) reported that shRNA knock-down of L1-CAM in CD133+ glioma cells significantly reduced neurosphere self-renewal potential, increased apoptosis, but inhibited proliferation of CSCs. L1-CAM silencing suppressed tumor growth and increased survival in an in vivo xenograft mouse model (Bao et al., 2008). This silencing was associated with reduced expression of Olig2, but increased expression of the p21 (WAF1/CIP1) tumor suppressor, suggesting their possible involvement in the CD133+ driven mechanistic effects in glioma cells.