Effect of prefreezing or postthawing cytokine stimulation on CFU-Meg expansion from 10⁴ CD34⁺ MNC. (A) CFU-Meg from cells cultured immediately. (B) CFU-Meg from cells cultured serum-free for 48 hours in the presence of TPO + KL + IL-1a + IL-3. (C) CFU-Meg from cytokine stimulated MNC before cryopreservation. (D) CFU-Meg from cytokine stimulated MNC after thawing. Data are pooled from four independent experiments, each performed in quadruplicate.