To characterize genes involved in megakaryocytic commitment, we compared expression profiles of bipotent cells (UT-7/c-mpl) with those of the same cells induced to differentiate towards megakaryopoiesis in the presence of TPO. Using cDNA arrays, we showed that 12 out of 2260 genes changed their expression level after 6 h of TPO stimulation. One of these genes encodes for zyxin, a cytoskeleton protein component. Zyxin is up-regulated at the mRNA and protein levels ill UT-7/c-mpl cells ill response to TPO confirmimg the reliability of the cDNA array technology. Similarly, when CD34 positive cells were induced to differentiate into megakaryocytes. zyxin mRNA was accumulated. Furthermore, when megakaryocytes were allowed to spread on fibrinogen, formation of stress fibers and lamellipodia was induced and zyxin was localized at the picks of actin stress fibers. These results suggest an important role for zyxin during megakaryocytic differentiation and more precisely ill the regulation of the integrin mediated adhesion process in megakaryocytes. (C) 2004 Elsevier Inc. All rights reserved.