MMP1 and esophageal squamous cell carcinoma: Several other recent studies demonstrated that miR-99 modulates many molecular signaling pathways that are not limited to AKT, mTOR, MMP1 and IGFR1 signaling and contribute to the tumorigenesis of cancer conditions such as head and neck squamous cell carcinoma [167], oral squamous cell carcinoma [168, 169] and esophageal squamous cell carcinoma [169].