Frontiers in Bioscience-Elite (FBE) is published by IMR Press from Volume 13 Issue 2 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
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Glioblastomas (GBM) are paradigmatic for the investigation of cancer stem cells (CSC) in solid tumors. Recently, the discovery of CD133- CSC in addition to CD133+ CSC has substantially added to our understanding of the complexity of GBM CSC. This review gives an overview on our current knowledge on CD133- cells in GBM and describes five different hypothesizes on the nature of CD133- cells in GBM. In addition, we summarize the current knowledge on tumorigenic CD133- CSC, list available markers, describe the current controversies on the origin of CD133- CSC, and discuss how the heterogeneity of CSC may correspond to the molecular heterogeneity of GBM.