Abstract
Epidermal growth factor (EGF) activates a well-characterized signal transduction cascade in most cell types and this activation leads to increase cell proliferation. Among the early effects envoked by EGF are the kinase activation of EGF receptor, the activation of mitogen-activated protein (MAP) kinase cascade and early gene expression such as c-fos. Recently, it was reported that the gravity influences the signal transduction via EGF receptor. To examine the action site of microgravity on EGF signal transduction cascade, osteoblast-like MC3T3-El cells were cultured in the Cell Culture Experiment Module (CCE-7) of the sounding rocket TR-1A7. The EGF-induced phosphorylation of MAP kinase was not affected under short-term microgravity conditions in the sounding rocket compared with the controls grown on the ground. Unfortunately, the cell morphology became too worth to confirm the nuclear translocation of MAP kinase in this experiment.
