Targeted proteindegradation is a promising therapeuticstrategy,spearheaded by the anti-myeloma drugs lenalidomide and pomalidomide.These drugs stabilize very efficiently the complex between the E3ligase Cereblon (CRBN) and several non-native client proteins (neo-substrates),including the transcription factors Ikaros and Aiolos and the enzymeCaseine Kinase 1α (CK1α,), resulting in their degradation.Although the structures for these complexes have been determined,there are no evident interactions that can account for the high efficiencyof formation of the ternary complex. This evidence concerns the gene CSNK1A1 and plasma cell myeloma.