Elevated concentration of CstF64 towards G1/S phase transition might favor an interaction with symplekin, resulting in tethering the HCC and its catalytic endonuclease CPSF73 to the factors already bound to histone pre-mRNA, i.e. FLASH and the U7 snRNP [19]. This evidence concerns the gene CSTF2 and hepatocellular carcinoma.