METTL3 and cancer: Online prediction tool (http://m6a2target.canceromics.org [31]) showed that METTL3, a m6A “writer” protein, was among the potential m6A functional candidates regulating STEAP2 expression, while persistently positive relationship between METTL3 and STEAP2 expression was observed in most cancers, including PTC (Fig. 6A–C).