miR-34a is a regulator of the Notch ligand Dll1. Down-regulation of Dll1 expression by miR-34a negatively regulates cell proliferation, and induces apoptosis and neural differentiation in MB cells. In addition infection of adenoviruses carrying the precursor miR-34a induces neurogenesis, reduces tumor burden, and confers chemosensitivity in mice xenografts,. Here, DLL1 is linked to infection.