CD44 and neoplasm: To determine if xenografts maintained the protein phenotype of the original tumour, we used immunofluorescent labelling of cryosections to evaluate the expression of a panel of lineage (nestin, nf-200 and GFAP) and putative tumour progenitor/stem cell markers (CD15, CD44 and CD133) in xenografts alongside primary tumour tissue (Fig. 2c).