To investigate the impact of the expression of PTPN1 in the modulation of growth of human NB cells, SH-SY5Y cells were transiently transfected with specific siRNAs targeting PTPN1 for down-regulation (Fig. 1a), and phosphotyrosine content and MTS cell proliferation assays were performed 72 h after transfection. This evidence concerns the gene PTPN1 and neuroblastoma.