Cancers in the upper layers of the skin are sustained by a continually renewing supply of aberrant stem cells, known as cancer stem cells. In a paper appearing April 3 in the journal Nature, a team led by EPFL/ISREC professor Joerg Huelsken has identified how this supply of cancer stem cells gets topped up, showing that a critical protein involved in cell signaling is important to maintain their numbers. The discovery could lead to treatments that would target the protein, thus destroying the cancer stem cells and killing the tumors.