MSLN and cancer: However, in mesothelial cancer cells, MSLN is also present in the cell membrane.42 In lung adenocarcinoma, the expression pattern of the MSLN is cytoplasmic and heterogeneous.43,44 Whereas cytoplasmic expression is more than membrane expression in gastric cancer.45 Due to high expression in certain cancers and low expression in normal cells, mesothelin may be the right candidate for immune cell engineering therapies.46 The concern about the MSLN CAR is the soluble MSLN, which could occupy the scFv segment.