Comparitive gene expression in skin between mice maintained in microgravity (0g) and normogravity (1g) environment. Six male C57Bl/J10 mice were housed for 91 days in the specially designed Mouse Drawer System in weightlessness aboard the International Space Station. Three wild-type mice (WT) and three transgenic mice overexpressing the osteogneic factor PTN/OSF1 under the control of the human bone specific ostecalcin promoter (Tg) were used in the experiment. During the 3-month stay on the ISS 3 mice unfortunately died leaving 2 Tg and 1 WT. MDS tissue sharing program allowed several teams to study various tissues from these mice. Our aim was to investigate the effect of such a long period of microgravity on skin physiology by morphological biochemical and genomewide analyses by comparison to similar mice on ground. Gene expression in the skin of 3 space mice and of 3 ground mice was analyzed by microarray. As this unique experiment performed on 3 mice limits the power of statistical analyis as the transgene PTN/OSF1 was not overexpressed in skin and as a pair wise Pearson s correlation rates between the individual levels of expressed transcripts in the WT and the Tg mice were not significantly different from each other in one experimental group (space or ground) data from the 3 mice were combined to compare results from the space an ground groups.