CTSK and neoplasm: These tumours showed similar patterns of immunoreactivityto tumours obtained from whole sphere populations when stained with antibodies against PMEL, SMA, PDGFRβ, CATHEPSIN K, NG2 and S100, as well as displayed E-CADHERIN positive epithelial structures (Fig. 2e and Supplementary Figs. 4a, b and 7c).