FOLH1 and melanoma: Glutamate can be produced, for example, through Δ1‐pyrroline‐5‐carboxylate (P5C) derived from the amino acids proline and ornithine.24 However, a recent study of melanoma has reported that intracellular P5C is rapidly converted to proline and thus glutamate production from this source is limited.25, 26 Alternatively, the metabolite N‐acetylaspartylglutamate has been shown to produce glutamate in pancreatic cancer both in vitro and in vivo via glutamate carboxypeptidase II (GCPII)‐catalyzed hydrolysis.27