Decreased growth of GFP⁺ human CB cells in vitro. (A) Experimental outline. (B) Unsorted CD34⁺ CB cells were plated in serum-free media. At given time points, GFP percentages were analyzed by FACS, and cells were counted and passaged. Data represent fold increase in number of cells ± SEM (n = 3). *P = .05 (paired Student t test). (C) FACS analysis showing CD34/CD90 expression after 7 and 15 days (D) of culture.