Specifically, Slug directly enhances MMP1 transcription in breast cancer cells (Shen et al., 2017a) as well as MMP9 in oral squamous cell carcinoma (Joseph et al., 2009), and Snail upregulates MMP9 in MDCKs (Jordà et al., 2005). Here, MMP9 is linked to oral cavity squamous cell carcinoma.