For example, Hazra et al. sought to ascertain if expressing dCK double (R104M and D133A) or a triple (R104M, D133A, and S74E) mutants in cancer cells would increase the sensitivity of dCK to non-natural substrates like pro-drugs bromovinyl-deoxyuridine (BVdU) or L-thymidine (LdT) [128]. Here, DCK is linked to cancer.