RECK and odontogenic neoplasm: Our study showed that MMP-2 protein expression and transcriptional levels sequentially increased in KCOT, ameloblastoma and ameloblastic carcinoma, and expression levels of MMP-2 protein and mRNA were significantly higher in ameloblastoma than in KOCT, or just the opposite of RECK, indicating that MMP-2 protein expression and transcription sequentially increased with the aggressiveness of odontogenic tumor cells.