In mouse model, gavage of Lactobacillus rhamnosus GG before radiation repositioned COX‐2 expression through TLR‐2/MyD88 signalling and reduced epithelial apoptosis and crypt loss from radiation injury.28 In patients, prevention of radiotherapy‐induced mucositis by probiotics has been investigated in several clinical trials.29, 30 Although the results were inconsistent, and strong evidence is lacking, there was still some promising data. The gene discussed is TLR2; the disease is mucositis.