Histograms of bcl-x-FITC and bcl-x_L-FITC staining after the immunomagnetic selection of CD34⁺ and CD34⁺/CD38⁻ cells from MPB. The left-hand histogram represents the negative control (mIgG), the middle empty histogram is the CD34⁺ cells expressing bcl-x and the filled-up histogram is the CD34⁺/CD38⁻hematopoietic precursors expressing high intensity bcl-x_Lprotein. Cells stained for bcl-x and bcl-x_L were first stained with anti-CD34-PE antibody then permeabilized with Ortho Permeafix. MNCs stained with mIgG were also permeabilized.