CD274 and osteosarcoma: Lin et al. elucidated that in osteosarcoma, MerTK-mediated phagocytosis promotes macrophage M2 polarization and PD-L1 expression via the p38/STAT3 pathway, intensifying immune tolerance and tumor progression, emphasizing the adverse impact of M2 polarization in increasing tumor aggressiveness (Lin et al., 2022).