TTR and squamous cell carcinoma: In support of this possibility, previous studies have reported that renal cell carcinoma, squamous cell carcinoma and breast cancer cell lines may produce and secrete common plasma proteins such as albumin, prealbumin, alpha-1-antitrypsin, ceruloplasmin, alpha-2-macroglobulin, haptoglobin, transferrin and alpha-1-antichymotrypsin [35], [36].