Interestingly, analysis with the GEO2R tool [33–35] of the microRNA array cohort data (GSE37407) which contains global miRNA expression profiling of 47 tumor samples from 14 patients with paired samples from primary breast tumors and corresponding distant metastases revealed that three micro-RNAs known to target MMP1 (specifically, miR-202-3p, miR-623 and miR-145) are downregulated in brain metastatic tumors compared to primary tumors [33, 36]. Here, MMP1 is linked to neoplasm.