MMP9 and cholesteatoma: In case of MMP9 mRNA expression was significantly elevated in recurrent cholesteatoma samples compared to the normal skin (μ±SD = 1.351 × 10−1 ± 0.276 for recurrent cases and μ±SD = 1.046 × 10−1 ± 0.2336 for control samples; the K-W test followed by Dunn’s P< 0.05) (Fig 2A).