With Nanopore RNA-m<sup>6</sup>A-sequencing, we unveiled that MTHFD1L fulfills these bi-functions by fueling methionine cycle that produces methyl groups to maintain the mRNA m<sup>6</sup>A of Snail (an HCC early tumorigenesis driver) and B2m (a light chain of MHC-I required for antigen presentation to CD8+ T) in HCICs. The gene discussed is B2M; the disease is hepatocellular carcinoma.