PPM1D and neuroblastoma: Protein phosphatase 2A (PP2A), protein tyrosine phosphatase receptor delta (PTPRD) and dual specificity protein phosphatase 12 (DUSP12) have been found to be involved in NB cell differentiation and tumor suppression.11, 12, 13, 14 First discovered in breast cancer, PPM1D, or Wip-1 phosphatase, is active in NB, and small molecule inhibition results in p53 activation and chemosensitivity.15, 16, 17 In this report, we show DUSP26 functions by inhibiting p53 and p38 function to promote growth of NB tumor cells.