01515nas a2200301   4500000000100000000000100001008004100002260001500043653002100058653001200079653001700091653002000108653002200128653003000150653003800180653001100218653001400229653002600243653001500269653002700284100001800311700001700329245003200346300001400378490000700392520080000399022001401199       2017                            d  c2017-10-0610aAdult Stem Cells10aAnimals10aCell Lineage10aCell Plasticity10aCell Self Renewal10aDrug Resistance, Neoplasm10aEpithelial-Mesenchymal Transition10aHumans10aNeoplasms10aNeoplastic Stem Cells10aStem cells10aTumor Microenvironment1 aEduard Batlle1 aHans Clevers00aCancer stem cells revisited  a1124-11340 v233 aThe cancer stem cell (CSC) concept was proposed four decades ago, and states that tumor growth, analogous to the renewal of healthy tissues, is fueled by small numbers of dedicated stem cells. It has gradually become clear that many tumors harbor CSCs in dedicated niches, and yet their identification and eradication has not been as obvious as was initially hoped. Recently developed lineage-tracing and cell-ablation strategies have provided insights into CSC plasticity, quiescence, renewal, and therapeutic response. Here we discuss new developments in the CSC field in relationship to changing insights into how normal stem cells maintain healthy tissues. Expectations in the field have become more realistic, and now, the first successes of therapies based on the CSC concept are emerging.  a1546-170X