Most importantly for discussions of microgravity-induced muscle atrophy, MuRF1 null mice have been used in the hindlimb suspension model, which has been advocated as a surrogate for space travel-induced atrophy, since it induces unloading of skeletal muscle, and the loss of MuRF1 has proven to be protective5,17. Here, TRIM63 is linked to muscle atrophy.