Human 293T cells were transfected with plasmid expressing the indicated wild type and mutant SAMHD1 protein. Cells were lysed 24 hours after transfection (Input), were incubated with ISD-PS immobilized in StrepTactin Superflow affinity resin. Similarly, eluted proteins from the resin were visualized by Western blotting using anti-FLAG antibodies (Bound). Similar results were obtained in three independent experiments and a representative experiment is shown. ISD-PS, interferon-stimulatory DNA sequence containing a phosphorothioate backbone; WB, Western blot; WT, wild type.