PARP1 and hepatocellular carcinoma: Specifically, UBQLN4 is reported to repress homologous recombination repair and promotes sensitivity to PARP1 inhibition23, while RRB2M, a gene that appears to promote tumorigenesis in hypoxic conditions and encodes a component of the ribonucleotide reductase, may be targeted by gemcitabine34, a chemotherapeutic agent sometimes used to treat HCC.