FBXO32 and Atrophy: Interestingly, Baehr et al. reported that the loss of muscle mass caused by 14 days of administration of the synthetic glucocorticoid (GC) dexamethasone is reduced in MuRF1, but not atrogin-1/MAFbx knockout mice indicative for a distinct role of both E3 ubiquitin ligases in different atrophy conditions.