Studies have shown that miR-99a-5p acts as a tumour suppressor and exerts inhibitory effects in several tumour cells, such as in human oral lymphoid carcinoma cells TSCC1, and miR-99a-5p can affect the proliferation, migration and invasion of human oral cancer cells by inhibiting NOX4 expression [26]. This evidence concerns the gene NOX4 and lip and oral cavity carcinoma.