CD274 and neoplasm: While physiological JAK/STAT signaling is essential for antitumor immunity, its persistent aberrant activation promotes malignant progression, upregulates PD-L1 expression, and orchestrates an immunosuppressive landscape by recruiting myeloid-derived suppressor cells (MDSCs) and polarizing tumor-associated macrophages (TAMs) toward an M2 phenotype, ultimately leading to T cell exhaustion.