Effect of PF4 and various peptides (p34-58 and p34-58ALA) on the formation CFU-MK. Values are expressed as the mean ± SEM of triplicate determination obtained from three separate experiments. *P < .01 as compared with control value determined by the Student's t-test. One hundred percent (100%) corresponds to the number of megakaryocyte colonies (52 colonies/mL) in control cultures.