USP50 and COVID-19: There are a number of other ACE2-phosphorylating kinases and enzymes that affect its ubiquitination, such as casein kinase 1 α (CK1α) [42], NUAK family kinase 2 (NUAK2) [42], MAP4K3 (GLK) [89], E3 ligase UBR4 [42] and ubiquitin-specific peptidase 50 (USP50) [42], whose expression was increased in COVID-19 patients [42], but their association with AD has not been shown.