VDR and Atrophy: We found that VDR is induced by simulated microgravity and translocated to the nuclei without addition of exogenous ligand, that VDR binding elements are associated with enhancers that are inactivated by simulated microgravity, and that VDR-deficient C2C12 myotubes established using the CRISPR/Cas9 system are resistant to simulated microgravity-induced atrophy.