ODN uptake over a 6-hour incubation period. (•) 2 μmol/L 5′CH-2B494AS-3′F; (⧫) 20 μmol/L 5′F-2B494AS; (▪) 20 μmol/L 5′DD-2B494AS-3′F; (*) 20 μmol/L 5′PEG5-2B494AS-3′F; (▴) 20 μmol/L 5′PEG2-2B494AS-3′F; (▵) 20 μmol/L 5′POE-2B494AS-3′F; (+) 2 μmol/L 5′VITE-2B494AS-3′F; (○) 20 μmol/L 5′F-2B494AS with SL-O.