Ribozyme uptake kinetics in JMML cells. The cells were transfected with two types of liposomes, one containing the ribozyme Rzd (1 μmol/L) and one containing a 20-nucleotide fluorescein-labeled oligonucleotide (0.2 μmol/L). Samples were taken at various time points and cell-associated fluorescence was analyzed with flow cytometry. Values are the means ± SEM from triplicate measurements of JMML cells taken from 1 patient and representative of the 2 other patients.