NSUN2 regulates downstream target gene expression, especially GRB2. A. The mRNA expression of m5C writers and readers in HCC tissues was higher than that in the adjacent tissues, determined by the transcriptomic analysis, ***, P < 0.001. B. In HCC cell lines, the UHPLC-MS/MS analysis showed that downregulation of NSUN2 did not change the density of m5C/C in total RNA. C. Real-time PCR analysis showed that the mRNA expression levels of GRB2, RNF115, and AATF were significantly lower in Huh7 NSUN2 knockdown cells, *, P < 0.05; **, P < 0.01. D. The m5C modification in the 3′ UTR and the expression of GRB2 mRNA were analyzed by IGV visualization in HCC tissues and the adjacent tissues. UHPLC-MS/MS, ultra-high performance liquid chromatography-mass spectrometry/mass spectrometry; UTR, untranslated region; IGV, itegrative genomics viewer.