- Establishment and characterization of a melanoma cell line from a xeroderma pigmentosum patient: activation of N-ras at a potential pyrimidine dimer site. Keijzer, W., Mulder, M.P., Langeveld, J.C., Smit, E.M., Bos, J.L., Bootsma, D., Hoeijmakers, J.H. Cancer Res. (1989)