GLS and melanocytic neoplasm: In this study, we evaluate the presence of major components of glutamine metabolism in canine oral malignant melanoma (OMM) and histologically well-differentiated melanocytic neoplasm of the lips and oral mucosa (HWDMN), also known as melanocytic tumors of low malignant potential: metabotropic glutamate receptor 1 (mGluR1/GRM1) and glutaminase (GLS1/GLS).