2013, Ganguly and Swarnakar 2009). Rudra et al. (2013) showed in a gelatin zymographic analysis a reduction of active MMP‐9 in the presence of melatonin. In a computer simulation, the protein sequences of MMP‐9 and melatonin revealed potential interaction sites (Rudra et al. 2013). Ganguly showed a direct enzymatic downregulation of secreted MMP‐3 and MMP‐9 by melatonin using gelatin and casein zymography in mouse gastric ulcer healing (Ganguly and Swarnakar 2009). This evidence concerns the gene MMP9 and gastric ulcer.