CAPN2 and chronic kidney disease: Also, calcium-dependent calpains (calpain 1, μ-calpain; calpain 2, m-calpain) are activated in hypoxic conditions [28], as well as in CKD associated with the induction of hypoxia factors 1-α, such as HIF1α, HIF2α, HIF3α which may contribute to muscle atrophy, muscle wasting and frailty [19] involving oxidation of contractile proteins, actin and myosin [26].