Huang et al. showed that down regulation of c-Jun and NF-κB inhibits the invasion of melanoma cells through suppression of MMP-944 None of our predicted networks included the MMP9 gene, however the interactions annotated in the STRING-DB are not all direct, and further investigation may identify a role for MMP-9 in metformin’s anti-cancer activity. This evidence concerns the gene MMP9 and cancer.