Our previous studies have illustrated that arginine deprivation achieved by treatment with arginine deiminase (ADI‐PEG20) can suppress tumor growth in 70% melanomas due to their low or no expression of argininosuccinate synthetase 1 (ASS1), an essential enzyme needed to generate arginine from citrulline (Feun et al., 2008). The gene discussed is ASS1; the disease is neoplasm.