Casein kinases are operationally defined by their preferential utilization of acidic proteins such as caseins as substrates. It can phosphorylate a large number of proteins. CSNK1A1 participates in Wnt signaling and phosphorylates CTNNB1 at 'Ser-45'. It may play a role in segregating chromosomes during mitosis. Recombinant human CSNK1a1 protein, fused to His-tag at N-terminus, was expressed in E.coli.