PTPA and medulloblastoma: Flow cytometric analysis of Annexin V revealed a remarkably significant decrease in apoptosis selectively in irradiated ES cells with depletion of PP2A activity by chemical inhibition (Fig. 5a1) and expression by RNAi (Fig. 5a2), while no protective effect was observed in medulloblastoma (Fig. 5b and Supplemental Fig. 5A) and glioblastoma cancer cells (Fig. 5c and Supplemental Fig. 5B).