Increased expression of CDK5, p35 or p39 and the resulting hyper-activation of CDK5 have been reported in pancreatic, medullary thyroid, non-small cell lung, small cell lung, colorectal, liver, breast and ovarian cancers, glioblastoma multiforme, multiple myeloma and mantle cell lymphoma [40,59–66]. Here, CDK5 is linked to AL amyloidosis.