FBXO31 and muscle atrophy: Furthermore, the mRNA levels of ubiquitin ligases [e.g., Atrogin‐1, muscle ubiquitin ligase of SCF complex in atrophy‐1 (i.e., MUSA1) and F‐box protein 31 (i.e., Fbxo31)], which are known to induce muscle atrophy,23, 24 were increased in the DEX‐treated cells, and KLF13 knockout augmented these effects (Figure5B).