To date, the study of Moon and co-workers has demonstrated the potential of hair follicle McSCs to form tumors in the well-known Tyr-CreER; BrafCA/+(BrafV600E/+); Ptenfl/fl (Tyr-CreER:Braf:Pten) murine melanoma model5,7, whereas the study by Kohler et al.6, using the same mouse, demonstrated their lack of tumor-forming capacity. Here, PTEN is linked to melanoma.