MAPK1 and neuroblastoma: Meanwhile, there are several genes which mediate the miR-34a induced tumor growth inhibition, such as BCL2, E2F3 and MYCN in neuroblastoma [52], [54], mitogen-activated protein kinase kinase 1 (MEK1) in human chronic myelocytic leukemia cell line K562 [53] and SIRT1 in prostate cancer PC3 cells [58].