NTRK2 and lung cancer: The expression of BDNF and TrkB by Western blotting was significantly increased in WT A549 lung cancer cells xenografted mice PFC compared to WT mice PFC, whereas the expression in TNFR2 KO mice xenografted with A549 lung cancer cells PFC was not significant compared to TNFR2 KO mice PFC (Fig. 5C).