The results of the time-course analysis of the changes in the expression of inflammation-related genes associated with RAS in the novel stomatitis-initiation model showed that the expression of cyclooxygenase-2 (Cox-2), tumor necrosis factor-α (Tnf-α) and interleukin-6 (IL-6) mRNA were significantly increased at 48 h after STI (24 h after the second STI) (p = 0.0295, 0.0185 and 0.0167, respectively) (Fig 8B). Here, PTGS2 is linked to stomatitis.