For instance, arginase (ARG1) and nitric oxide synthase (NOS2) influence macrophage polarization: M1 macrophages metabolize arginine to nitric oxide (NO) via NOS2 to exert anti-tumor effects, whereas M2 macrophages convert arginine to urea, polyamines, and ornithine through ARG1 in response to tumor stimuli (Yerushalmi et al., 2006; Ou et al., 2023). This evidence concerns the gene NOS2 and neoplasm.