Cytokine stimulation of CD34⁺ cell expansion into CD41⁺ megakaryocytes. CD34⁺cells were cultured in various cytokine mixtures, composed of IL-1, -6, -11, SCF (S), and/or Thrombopoietin (T). Fold-increase values are mean ± SEM (n = 3). Input numbers of CD34⁺/CD41⁺ cells were 667 ± 289 per culture (n = 3). *P ≤ .05 compared with IL-1,6,11,S-driven CD41⁺ cell expansion in the absence of TPO.