RPAP2 and hepatocellular carcinoma: Given that FBXW7 is a negative regulator of tumor growth[17] and RPAP2, a novel FBXW7 substrate, is required for the growth and survival of HCC cells (Figure 1; Figures S1,S2, Supporting Information), we investigated whether RPAP2 accumulation plays a causal role in the tumor growth induced by FBXW7 knockdown.