Using chromatography-mass spectrometry on an Ultimate 3000 chromatograph combined with a Maxis 4G mass spectrometer, the secretome of human umbilical vein endothelial cells (HUVEC) cultured under static conditions and modeling microgravity for 24 hours was studied. In the secretome of cells under microgravity conditions, a group of microtubule proteins was identified, among which many structural elements of microtubules, as well as regulatory proteins interacting with Rho-GTPases. Thus, the reorganization of actin cytoskeleton and microtubules caused by microgravity is under a complex regulation mediated by Rho proteins.