MMP1 and neoplasm: To comprehend this process, a team of researcher performed a tumor self-seeding mouse model experiment whereby tumor recurrence intervened by CTCs was examined utilizing human colorectal, melanoma and breast cancer cell lines, and found that tumor-derived cytokines IL-6 and IL-8 act as CTC attractants which were mediated by MMP1, FSCN1, and CXCL1 genes expressed on CTCs to promote infiltration [98].