MCF7 cells transfected with miRNAs, siRNAs or LNAs were treated with 10 μg/ml DQ Red BSA (D-12051, Invitrogen) for 12 h at 37 °C. Samples were cultured in normal medium or EBSS solution to induce nutrient starvation. The fluorescent images of DQ Red BSA were acquired by confocal microscopy and the fluorescence intensity was measured by Image J software (National Institute of Health, Bethesda, MD, USA, http://imagej.nih.gov/ij/).