The use of the random positioning machine for the study of gravitational effects on signal transduction in mammalian cells

A comprehensive survey is provided on the application of a random positioning machine (RPM) for studies on gravitational effects on mammalian cells. The RPM is suitable to simulate microgravity conditions and allows performing a high number of on-ground experiments wherein mammalian cells are exposed to reduced gravity. Most of these experiments have been performed either to prove or extend observations made during spaceflights or to develop and prepare new spaceflight experiments. They did not only bring a tremendous number of observations, but they helped to elucidate three dominant cellular pathways that are affected by weightlessness. The apoptotic, the immune-activating and the bone differentiation pathways are discussed.