TLR2 and fibrosis: Paun and colleagues analyzed the effects of 18Gy (Gray) WTI on the development of pneumonitis or fibrosis in mice deficient for TLR2 (TLR2−/−), TLR4 (TLR4−/−), and TLR2/4 double knockout mice (TLR2−/−/TLR4−/−) [161].