Increased activity of Cdc42 in primitive hematopoietic cells in aged mice. (A) BM cells from young (2- to 4-month-old) and aged (20- to 27-month-old) mice were subjected to an effector domain pull-down assay and subsequently probed by immunoblotting. (B) Quantification of the relative amount of the active Cdc42-GTP bound form by densitometry. n = 3 for young mice, and n = 4 for aged mice. Values shown are mean ± 1 SEM. *P < .05. (C) Lin–BM cells (enriched for HPCs) isolated from pooled BM cells from each experiment in which 4 young, middle-aged, and aged mice (2, 13, and 22 months, respectively) were subjected to an effector domain pull-down assay and subsequently probed by immunoblotting. Data are representative of 2 independent experiments.