Inhibition of colony formation of JMML cells supplemented with ribozymes. JMML cells were plated for 2 weeks either alone (none), with only liposomes (DOTAP), or with ribozymes (Rzd/Rzdm). (A) The ribozyme Rzd markedly reduced JMML cell colony formation, whereas the ribozyme mutant Rzdm had less pronounced effects. (B) Exogenous supply of either GM-CSF (10 ng/mL) or TNF (10 ng/mL) abolished the inhibitory effect of Rzd and profoundly increased JMML cell colony numbers. Triplicate measurements were made from each of the 3 patients, and the obtained median values were used to calculate the mean + SEM shown. Note the different abscissa values in (A) and (B). (░) Patient no. 1; (▪) patient no. 2; (□) patient no. 3.