CLINICAL IMPLICATIONS: Despite the improvements in diagnosis, surgical techniques, and local and systemic adjuvant therapies, lung cancer still remains a major worldwide health problem. And, most deaths from cancer result from the progressive growth of metastases. Recently, the effects of microgravity on cell morphology, structure, functions and their mechanisms have been widely studied. And, considering the limitations of performing experiments in real microgravital environment on Earth, random positioning machines named “clinostat” have been developed in order to create “simulated microgravity” environment. Although there were previous reports on the biological effects of simulated microgravity on different types of cancer cells, the effects of simulated microgravity on the process of human lung cancer metastasis has not been revealed sufficiently. Considering the many different subtypes and different cell lines in human lung cancer cells, our study may suggest informations on how cancer cells' metastatic ability might change during the microgravital environment.