PLAU1 overexpression significantly enhanced the proliferation, colony-formation ability, and invasion ability of Cal27 and HN30 cells, while siRNAs against MMP1 (5’-CCCTAGAACTGTGAAGCATATCG-3’) partially inhibited PLAU1 overexpression-induced cell proliferation (Figure 6A), colony-formation ability (Figure 6B), and invasion ability (Figure 6C), suggesting that PLAU1 affects the proliferation, colony-formation ability, and invasion ability of HNSCC cells via interaction with MMP1. This evidence concerns the gene MMP1 and head and neck squamous cell carcinoma.