Inhibition of luciferase activity production at 4°C or 37°C and by endocytic pathway inhibitors upon 2′-OMeUtaPS-mediated internalization of PMO sequence 10 in both serum-containing and serum-free media. For each experiment, the extracellular concentrations of 2′-OMeUtaPS and sequence 10 are 2.0 μM and 1.0 μM, respectively, whereas the extracellular concentrations of nystatin, latrunculin, cytochalasin D, chlorpromazine and EIPA are 30 μM, 2 μM, 2 μM, 50 μM and 0.5 mM, respectively. Error bars represent the mean ± SD of three independent experiments. EIPA = 5-(N-ethyl-N-isopropyl)amiloride; RLU = relative light units; FBS = Fetal Bovine Serum.