RET and lung adenocarcinoma: Transcriptome analysis of multiple lung adenocarcinoma patients using next-generation sequencing (NGS) recently showed the existence of a fusion gene containing the tyrosine kinase domain of the c-RET oncogene in 1%–2% of patients; this fusion leads to aberrant activation of RET kinase and is considered to be a new driver mutation of lung adenocarcinoma [5].