BDNF and esophageal squamous cell carcinoma: Indeed, in lung cancer (Gomez et al., 2018), head and neck cancer (Jiang et al., 2017), and esophageal squamous cell carcinoma (Gomez et al., 2018), BDNF/TrkB/PI3K-AKT seem to be activated and linked to invasiveness (Figure 3B).