Recent studies indicate that epigenetic regulation and RNA modifications, such as METTL1-mediated m7G methylation, can modulate the expression of immune-related genes and the function of immune cells, offering new insights into the complex regulation of the TME.In HCC, the tumor cell-intrinsic roles of METTL1 in regulating PMN-MDSCs have recently been elucidated. The gene discussed is METTL1; the disease is neoplasm.