Administration of CB-1158 (a small molecule inhibitor of arginase) can slow tumor growth rates, block myeloid cell-mediated suppression of T-cell proliferation, and increase the number of tumor-infiltrating CD8+ T cells and NK cells in mouse models of multiple tumors.190 Piceatannol (PIC), another natural arginase inhibitor, can effectively inhibit TGF-β1 /TGF-β receptor type 1 (TGF-βR1) signaling pathway, limit M2-type macrophage polarization to regulate TME and inhibit CRC progression and metastasis.191 These results suggest that ARG is a potential target for tumor metabolism. The gene discussed is CD8A; the disease is neoplasm.