SIRPA and melanoma: In 3D cultures with CAR-MαCSPG4, we observed almost 50% of CAR-Ms were positive for Lck-mScarlet fragments at 24 hours, with a higher proportion of CAR-Ms with large, internalized melanoma fragments when the CD47/SIRPα axis was inhibited with αCD47 compared to those treated with IgG isotype control antibodies (Supplemental Fig. 5a).