ARG1 and neoplasm: A less pronounced, but nevertheless significant reduction of tumor growth upon OAT-1746 treatment was also observed in the control group with ARG1-negative tumors (Fig. 7a, for weight P = 0.0065, for waist circumference P = 0.0093, unpaired t-test), indicating potential blockade of arginase activity in MDSCs and TAMs, the other known sources of ARG1 in the TME.