While IL-22-dependent production of MMP-9 has been observed during the migration and invasion of gastric [69] and breast cancer cells [70], the limited effect observed in THP-1 cells may be ascribed to the utmost weak expression of one of the two receptor subunits (IL-22R1) necessary for IL-22 signaling in THP-1 [71]. Here, MMP9 is linked to breast carcinoma.