PTGS2 and oral mucositis: The mechanisms involved in oral mucositis include apoptosis of submucosal cells, activation of macrophages and transcription factors [for example, nuclear factor kappa B (NF-κB)], and elevation of pro-inflammatory cytokines [such as tumor necrosis factor (TNF-α), interleukin 1 beta (IL-1β), cyclooxygenase-2 (COX-2), and matrix metalloproteinases].