In contrast to our data using SCLC, cell surface expression of Thy-1 was reported to be enriched in CD133+ tumour stem cells from brain tumours (Liu et al, 2006; Mizrak et al, 2008) characterised by self-renewal, high proliferative capacity in vitro and tumour reconstitution in vivo (Al Hajj et al, 2003; Ponti et al, 2005; Sales et al, 2007; Eramo et al, 2008). This evidence concerns the gene PROM1 and small cell lung carcinoma.