PRKN and amyotrophic lateral sclerosis: Our team previously identified that the cyclin F p.S621G mutation causes an increase in its E3 ubiquitin ligase activity for Lysine(K)48-linked polyubiquitylation [19–21] which leads to the accumulation of ubiquitylated ALS-associated protein TDP-43 and SCFcyclin F target protein RRM2 in neuronal cells [2].