FOXD1 and neoplasm: In particular, the authors observed a decrease of MMP-9 expression by using a siRNA against FOXD1. In addition, the loss/down-regulation of RAC1B decreases the spreading of tumor cells and delays the Epithelial–Mesenchymal Transition, underlying the importance of the FOXD1-RAC1B axis in the regulation of MMP-9-mediated melanoma cells invasion [74].