NTRK2 and neoplasm: For example, neurogenic differentiation 1 (NEUROD1) which plays a crucial role in the development and differentiation of nerve cells [13], has been shown to promote the progression and metastasis of small cell lung cancer (SCLC), which has NE characteristics, by regulating the receptor tyrosine kinase B (TrkB) and neural cell adhesion molecule (NCAM) in tumor cells [14].