In a similar way, millimolar melatonin reduced the migration and metastatic invasion of nasopharyngeal carcinoma cells through the suppression of MMP-9 expression by inhibiting the binding of the transcription factor, specificity protein-1 (SP-1) to DNA at the MMP-9 promoter [91] (Table 3). This evidence concerns the gene SP1 and nasopharyngeal carcinoma.