ASS1 and melanoma: Finally, there are tumors such as prostate (80–82) and lung cancer (83) as well as tumors that are auxotrophic for L-arg (these are not capable of re-synthesis of L-arg from citrulline due to the lack of expression of argininosuccinate synthetase-1, ASS-1), such as melanoma (84) and renal carcinoma (85, 86), where no correlation between ARG levels and survival has been found.