Maintenance of LTC-IC function through successive in vitro divisions under different cytokine conditions. Experimental (red data points) and predicted (blue plot) probability of detecting LTC-IC function among single sorted G₀CD34⁺CD38^–/lo cells was plotted for each of the 7 cytokine combinations segregating the data based on the number of cells contained in each well on day 5. Because few wells in all cases contained 9 or more cells, all data points in all the plots were pooled together and are reported here as 9 cells/well. Predicted values for each plot were calculated by regression analysis as indicated in “Materials and methods.” Experimental data points (red) are reported as mean ± SD. The number of cells in each well on day 5 was not a significant predictor of LTC-IC activity for all combinations (P > .05 for all) except combination 4 (SFM3; P = .033).