In breast cancer, the expression of ARG1 increases when GM-CSF stimulates the STAT3 or p38MAPK signaling pathway, and immune cells in the microenvironment obtain less L-arginine, which increases the phenotypic differentiation of TAMs to M2 macrophages, reduces the infiltration of CD8+ T cells and ultimately promotes immune escape (134). Here, CSF2 is linked to breast carcinoma.