NB1, SH-SY5Y, CLBGA, and NBL-S cells were transfected using Lipofectamine RNAiMAX (Invitrogen) according to the manufacturer’s instructions, and all the assays were performed 48 to 72 hours after transfection. Double-stranded siRNA oligonucleotides targeting human IRS2 (sequence #1: 5′-UCAUCCCACCCUGUUUCCCUGAAUU-3′; sequence #2: 5′-GGUCCAUCUUCAGAGAAGAAAUCAA-3′; sequence #3: 5′-CAUGGGAGAGGGUUAUGCCUUUGAA-3′; sequence #4: 5′-CCAGCAGAUUGAUAGCUGUACGUAU-3′) and human ALK (sequence #1: 5′-GACAAGAUCCUGCAGAAUA-3′; sequence #2: 5′-GGAAGAGUCUGGCAGUUGA-3′) were purchased from GE Dharmacon. Cells were transfected either individually or with a mixture of siRNA duplexes in equal amounts to a final concentration of 80 nM. As control, siRNA control duplex (siGENOME Non-Targeting siRNA pool #2) (GE Dharmacon) was used at a final concentration of 80 nM. Silencing of gene expression was monitored by Western blotting of cell lysates with an antibody against IRS2.