Complex of CRBN (Cereblon), DDB1(damage specific DNA binding protein 1), Cul4A (cullin 4A), and Rbx1 (ring-box 1) proteins. These recombinant proteins are co-expressed and affinity purified. Recombinant human CRBN, encompassing amino acids 2-442(end). This construct contains an N-terminal Flag-tag. Recombinant human DDB1, encompassing amino acids 2-1140(end). This construct contains an N-terminal Flag-tag. Recombinant human Cul4A, encompassing amino acids 2-759(end). This construct contains an N-terminal His-tag (6xHis). Recombinant human Rbx1, encompassing amino acids 2-108(end). This construct contains an N-terminal His-tag (6xHis).