PROM1 and melanoma: Tumor single-cell suspensions (for the composition see Figure S3A-C) from hRT- and hRT/lena-treated mice bearing B16-CD133 melanoma tumors were isolated at day 8 after treatment start and re-stimulated ex vivo with M8 peptide (the immunodominant epitope of the MuLV p15E tumor antigen presented by H-2Kb) for 4h in the presence of Brefeldin A. Brefeldin A was added to trap the effector cytokines within the TILs to enable detection by intracellular flow cytometry.