PTGFR and neoplasm: To evaluate antigen-specific responses, splenocytes from the different groups were stimulated in vitro with MHC class I H-2b restricted peptide epitopes for the tumor antigens CEA526-533 and CEA572-579, the endogenous retroviral tumor antigen gp70 (p15E), and MC38-associated neoepitopes for Jak1 and Ptgfr.21 IFN-γ ELISpot showed that the hexatherapy regimen promoted development of CD8+ T cell populations targeting all the immunogenic epitopes tested (figure 3E–I).