Effect of p18 knockdown on human hematopoietic cells. Representative images (A) and absolute numbers (B) of the flow cytometry data of human CD34⁺ and CD34⁺CD49f⁺ cell populations of hUCB CD34⁺ cells after infection of lentivirus carrying hairpin RNA targeting p18 were measured at 7 days (n = 3); 1 × 10⁴ CD34⁺GFP⁺ human UCB cells were seeded at the beginning. (C) Total CFC contents of control and p18 knockdown human CD34⁺ cells at 2 weeks (n = 3). GEMM, colony-forming unit-granulocyte, erythroid, macrophage, megakaryocyte; CFU-GM, colony-forming unit-granulocyte, macrophage; BFU-E, burst-forming unit-erythroid; CFU-E, colony-forming unit-erythroid. (D) Frequencies of CAFCs of control and p18 knockdown human CD34⁺ cells (n = 10). Doses of 30 000, 15 000, 7500, 3750, and 1875 cells per well were used. The experiment was repeated 3 times. All data represent the means ± standard deviation (SD). Compared with control unless specified: *P < .05, **P < .01, ***P < .001 by 2-tailed unpaired t test.