Comparison of transmigration of proliferating and nonproliferating CFCs in cytokine-activated peripheral blood CD34⁺ cells. Determination of CFC proliferation was done by ³H-thymidine assay as detailed in the Materials and Methods. Clonogenic assays were set up with both control and³H-thymidine–treated cells before and after transmigration, and percent migration of proliferating versus nonproliferating CFCs was then calculated as outlined in the Materials and Methods. Data are the mean ± standard deviation of five separate experiments.