Fig. 1. Scatter plot of gene expression by DNA microarray analysis. The whole gene expression profile is plotted as gray spots. Squares and triangles indicate muscle-related genes and their transcription factors, respectively. The closed squares indicate significantly lower expression in response to spaceflight. These groups include myosin heavy chain (MHC) isoforms, troponins and tropomyosins whereas the open squares include actins and non-muscle myosins.