Cells are sterile, validated by short tandem repeat profiling, and are tested as negative for mycoplasma. It is recommended that cell lines are tested for mycoplasma contamination and short tandem repeat (STR) profiling every 10 passages or each time a frozen seed stock is made. See cell culture protocol for additional details. WM3000 is a metastatic human melanoma cell line that displays a melanocytic morphology. This cell line contains a Q61R mutation at position 61 in the N-RAS gene. The Q61R is the most common NRAS mutation found in melanoma that is thought to occur due to UV and radiation exposure. This mutation leads to production of a constitutively active N-RAS protein that directs cells to grow and divide constantly. WM3000 cells are from same patient as WM 2032. These cells produce xenograft tumors when injected into immunocompromised mice.