METTL3 and nonpapillary renal cell carcinoma: Moreover, we also found HHLA2 mRNA (Fig. 3G) and protein (Fig. 3H and I) expression levels were significantly increased in METTL3-overexpressing ccRCC cells, but not in METTL3-Mut (W397A)-overexpressing ccRCC cells, suggesting the regulation of METTL3 on HHLA2 expression dependent on the m6A methylation ability of METTL3.