STAT3 and hepatocellular carcinoma: Then, Co‐IP assay was used to validate the binding between C21orf58 and STAT3, and results showed that C21orf58 interacted with STAT3 either exogenously or endogenously (Figure 4A and Figure S5B, Supporting Information), which was further confirmed by their colocalization in the HCC cells (Figure S5C, Supporting Information).