Dissociated single cell suspensions from primary tumors (as described previously (24 (link))) or cultured cells were incubated with Aldefluor reagent (Stem Cell Technologies) for 30 minutes according to manufacturer’s instructions. Cells were then rinsed before incubation with CD61-biotin for 20 minutes at 4°C. Following that, cells were rinsed and incubated with other antibodies marking CSCs for 20 minutes at 4°C. Cells were then rinsed and resuspended in Aldefluor buffer before sorting or analysis by FACSAria or FACSCanto instruments (BD Biosciences). Flow cytometry data were analyzed using FlowJo software.