MSH2 and neoplasm: The loss of function in core MMR genes such as muts homolog 2 (MSH2) and muts homolog 1 (MSH1) can lead to the upregulation of PD-L1 expression while activating the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, thereby inducing IFN-γ signaling to enhance tumor immunogenicity (49).