Effects of cytokine combinations on ex vivo expansion and gene transduction. (A) Fold expansions in cellularity, CFC in methylcellulose cultures (CFC-MC), LPP-CFC, and HPP-CFC induced under various cytokine combinations are illustrated. (B) The percentages of transduced nls-LacZ gene expressing colonies are summarized. (□) C1: IL-3 + IL-6 + GM-CSF + KL; (▧) C2: IL-3 + IL-6 + GM-CSF + KL + FL; (▪) C3: IL-6 + KL + FL. Numbers of fetal liver samples analyzed are shown in parentheses.