CD274 and neoplasm: Akin to solid tumors, MPNs express high levels of immunosuppressive proteins, such as PD-L1 and ARG1, as described above, whereas a highly variegated mutational spectrum is not characteristically observed in this group of neoplasms, since 80–90% of patients harbor either JAK2V617F or CALR mutations, which are thought to be relevant sources of shared neoantigens.