MSLN and neoplasm: The use of A431/H9 tumor which overexpresses both the shed Ag mesothelin and the nonshed Ag Lewis-Y as a tumor model and the use of anti-mesothelin mAb amatuximab and anti-Lewis-Y mAb B3 as model mAbs for the BD, PET, and autoradiography studies allowed us to make a direct assessment on the effect of the shed Ag on the tumor and organ uptakes and tumor penetration, apart from the effects of other factors related to the tumor microenvironment.