Response to Comment on "Tumor Growth Need Not Be Driven by Rare Cancer Stem Cells"

Abstract
A critical issue for cancer biology and therapy is whether most tumor cells or only rare “cancer stem cells” sustain tumor growth. Although the latter model seems supported by the minute proportion of human leukemia cells that can grow in immunodeficient mice, evidence that more than 10% of cells in many mouse leukemias and lymphomas are transplantable challenges its generality.