Ex vivo culture of PB CD34⁺ cells in serum-free pre-CFU media stimulated with 4 HGF or 4 HGF + FLT3L. The graph shows the number of CFU-GM (A) and nucleated myeloid cells (B) generated from 1,000 PB CD34⁺ cells after 14 and 21 days of culture. The results are the mean and standard errors from three cultures established with CD34⁺ cells obtained from cryopreserved apheresis collections following high-dose cyclophosphamide administration.