Compression-induced Pathohistology and Increase in MAFbx/atrogin-1. Preliminary experiments were conducted to expose untreated rats (neither DMSO nor MG132) to the compression protocol to examine the effect of compression on gross muscle histology and expression of ubiquitin E3 ligases, MAFbx/atrogin-1 and MuRF1. Gross muscle histology was examined following hematoxylin and eosin staining. Muscle tissue after compression generally showed pathohistological appearances including rounding shaped muscle cells, accumulated nuclei number, and internalization of peripherally located nuclei in muscle cells (as shown by arrows in B). Fluorescent immunocytochemical analysis demonstrated that the protein expression of MAFbx/atrogin-1 was apparently elevated in cytoplasmic region of the compressed muscle (D) relative to uncompressed muscle (C). No noticeable change in immunoreactivity of MuRF1 was found in the compressed and uncompressed muscles (data not shown).