Since NCI-H322 cells are a non-small cell lung cancer line and TrkB signaling is intimately linked to tumor progression (Nakagawara et al., 1994; Sinkevicius et al., 2014), including non-small cell lung cancer (Chen et al., 2016), it is possible that BDNF signaling mechanisms are altered in NCI-H322 cells or that club cell-derived BDNF acts in a juxtacrine/paracrine fashion on other cell types that are not represented in the NCI-H322 monoculture model. This evidence concerns the gene NTRK2 and small cell lung carcinoma.