TTBK1 and amyotrophic lateral sclerosis: Phosphorylation at Ser-379, Ser-403, Ser-404, and especially Ser-409/Ser-410 is mediated by kinases—such as casein kinase-1 and -2 (CK1 and CK2), cell division cycle 7 (CDC7), and tau tubulin kinase-1 and -2 (TTBK1 and TTBK2)—which leads to increased oligomerization and fibrillization of TDP-43 and is now considered a signature of TDP-43 pathology in ALS and FTLD-TDP [61].