Ectopic over-expression of wild type PTPRD suppresses the growth of human neuroblastoma cell lines by inducing cell apoptosis. (A) SHSY5Y (B) Kelly and (C) CHP-212 cells were transfected with PTPRD cDNA or empty vector (pcDNA3.1-V5) and were analysed by a Cyquant assay at 24, 48 and 72 h. All graphs report mean ± S.E.M., n = 3, ** p < 0.01, *** p < 0.001. (D) Kelly cells transfected with either empty vector or an expression plasmid containing PTPRD with a mutated phosphatase domain. PTPRD induced apoptosis was demonstrated by FACS analysis of annexin-V staining. Kelly cells were transfected with empty vector (E) or PTPRD cDNA (F). Cells were harvested 72 h post transfection. PI staining of DNA represents necrotic cells (upper left quadrant). Annexin V staining indicates cells that are early apoptotic (bottom right quadrant). Double stained cells (upper right quadrant) indicate cells in late apoptosis. Percentages of cells in each quadrant are shown.