HGF and lung adenocarcinoma: Furthermore, in addition to paracrine signalling of the c-Met receptor on NSCLC cells through HGF secretion by stromal fibroblasts, lung adenocarcinoma cells can also undergo autocrine signalling, raising the possibility that HGF could also play a role in TNT formation between cancer cells (Masuya et al, 2004; Nakamura et al, 2007).