Effect of RCC CM during the different phases of the culture. Double staining (CD14-PE/CD1a-FITC) was performed at day 12 and the results were compared for CD34⁺ cultured with cytokines alone (control) or in the presence of 10% RCC CM from day 0 to 6 (top right), from day 6 to day 12 (bottom left), or day 0 to day 12 (bottom right). Results are representative of four experiments.