In three separate experiments CD34⁺ cells were cultured in serum-free medium and a serially diluted mixture of growth factors in wells coated with H120 or H0 fragments. Growth factor concentrations ranged from standard concentration (IL-3 10 ng/mL, IL-6 200 U/mL, G-CSF 500 ng/mL, SCF 100 ng/mL, erythropoietin 2 U/mL) to$116$ concentration (IL-3 0.625 ng/mL, IL-6 12.5 U/mL, G-CSF 31.25 ng/mL, SCF 6.25 ng/mL, erythropoeitin 0.125 U/mL). Cells were counted at a mean of 11 days. Cell numbers with H0 were expressed as the mean percentage of expansion with H120 and the overall fold expansion with H120 compared with H0 is shown. Student'st-test was used to calculate P values.