PAK1 and cancer: PAK1 plays an important role in the regulation of actin cytoskeletal dynamics55, 56 and has been shown to promote myoblast differentiation and muscle regeneration as well as counteract muscle atrophy during cancer cachexia.57, 58 Thus, the up‐regulation of PAK1 is not likely to contribute to the reduction in myofibre CSA in MKO mice and may be a compensatory response to the reduced SRF signalling in MKO mice.