PBX1 and infection: Primary aNS were subjected to one of the following four treatments (1) infection with pCLIG, GFP-expressing retroviral vector viruses (vector ctrl)30, (2) infection with pCLIG expressing Pbx1 (transcript variant 1b; Pbx1OE), (3) transfection with non-targeting siRNAs followed by infection with pCLIG expressing Pax6 (Pax6OE), and (iv) transfection with siRNAs targeting Pbx1 followed by infection with pCLIG expressing Pax6 (Pax6OE/Pbx1KD).