BDNF and lung carcinoma: Immunohistochemical analysis revealed that the BDNF and TrkB reactive cell number between TNFR2 KO and TNFR2 KO mice xenografted with A549 lung cancer cells brains was not significant, whereas significant results were seen in WT and WT A549 lung cancer cells xenografted mouse brains (Fig. 5A and B).