Along these lines, our quantitative proteomic analysis of protein abundance revealed a prominent reduction in abundance of all subunits of hemoglobin in tumor tissue (Supplementary Data 2, 5) as well as a reduction in proteins responsible for maintaining proper lung function and integrity of the epithelial barrier, such as claudins28 (claudin-18), caveolins (CAV1 and 2)29, angiotensin-converting enzyme (ACE1 and 2)30 and others (Suppl. This evidence concerns the gene CLDN18 and neoplasm.