MMP9 and neoplasm: The presence of IL-17A promoted the formation of CTCs and motility by inducing the expression of matrix metallopeptidase 9 (MMP-9) in tumor cells, matrix degradation, and angiogenesis, whereas GM-CSF administration polarized the TAMs toward the M1 phenotype (an antitumor type), increased the M1/M2 (a protumor type) ratio, and thus, stimulated the elimination of CTCs by elevated number of CD4+ and CD8+ T lymphocytes and NK cells [49].