By contrast, genetic ablation of Arg2 expression in mice increases arginine levels in serum, secondary lymphoid organs and within the tumour microenvironment leading to an enhanced tumour infiltration of CD8+ T cells that results in a slower growth of MC38 colon carcinoma or B16 melanoma (Marti i Lindez et al. 2019). The gene discussed is CD8A; the disease is neoplasm.