Cell Culture and Transfection Protocol

The human cervical adenocarcinoma cell line HeLa (ATCC CCL-2), human hepatocellular carcinoma cell line HepG2 (Korean Cell Line Bank) and mouse neuroblastoma cell line Neuro-2a (N2a, ATCC CCL-131) were maintained in Dulbecco's modified Eagle's medium (DMEM; Gibco) supplemented with 10% fetal bovine serum (FBS, Gibco), 100 U ml⁻¹ penicillin, and 100 μg ml⁻¹ streptomycin at 37 °C with 5% CO₂ incubation. The mouse liver cell line NCTC clone 1469 (Korean Cell Line Bank) was maintained either in the same medium or with 10% horse serum (WelGENE) instead of FBS. NCTC clone 1469 cells were transfected by using Lipofectamine 2000 (Invitrogen), whereas HepG2 and N2a cells were transfected by using RNAiMAX (Invitrogen) with 50 nM RNA duplexes according to the general protocol provided by the manufacturer, unless otherwise indicated. Transfection into HeLa cells was performed as described previously26 (link). The cells were generally collected 24 h after transfection in all experiments, unless otherwise indicated.