MSLN and cancer: We did not expect complete protection from apoptosis of cells treated with Meso-TR3, even assuming 100% MUC16 blockade with soluble mesothelin, since all TRAIL variants (including TR3, recombinant rTRAIL and Meso-TR3) exhibit baseline apoptosis-inducing activities in MUC16-deficent cancer cells due to direct interaction of the TRAIL timer with cell surface DR4/5.