Leucine zipper-EF-hand-containing transmembrane protein 1 (LETM1), a mitochondrial endosomal protein, is highly expressed in many human malignancies, such as gastric adenocarcinoma [4], non-small cell lung carcinoma [5] and colorectal adenocarcinoma [6], and has a close relationship with poor prognosis. The gene discussed is LETM1; the disease is non-small cell lung carcinoma.