The synthetic sphingolipid FTY720 acts as a PP2A activator by binding the endogenous inhibitor SET and derepressing PP2A [36] Our lab has previously shown decreased neuroblastoma proliferation, motility, and in vivo tumor growth following small interfering RNA (siRNA) or short hairpin RNA (shRNA) knockdown of SET [8]. The gene discussed is SET; the disease is neoplasm.