PTN and neoplasm: Significantly, bioluminescent imaging and haematoxylin and eosin staining demonstrated that silencing PTN expression in MLCs significantly compromised the tumour-promoting effect of the co-implanted MLCs, resulting in the retarded tumour growth in GBM xenografts co-implanted with GSCs and shPTN MLCs relative to those co-implanted with GSCs and shNT MLCs (Fig. 2e,f and Supplementary Figs 2j and 3c).