Flow cytometric analysis of CD34 expression before and after culture. Sorted Lin⁻ c-kit⁺Sca-1⁺ CD34⁻ cells were stained with PKH26 and analyzed before culture (left). After 1 week of incubation with SF and IL-11, cells were analyzed for CD34 expression and PKH26 fluorescence (right). Dotted and solid lines represent cells stained with IgG_2a-FITC and CD34-FITC, respectively.