MMP9 and breast cancer: Nonetheless, we observed several possible regulators (e.g., FAK, MMP9, EMT) that could be involved in the mechanism of metastatic induction by Pgrmc1. First, we observed that genetic deletion or silencing of Pgrmc1 resulted in decreased expression of FAK, which was shown to negatively regulate invadopodia and positively regulate the invasion of breast cancer cells [27].