PARP2 and cancer: Furthermore, the ability of olaparib to exacerbate bone metastasis of Py8119 cells in WT mice was completely abolished in PARP2CKO mice (Fig. 1f), pinpointing that olaparib-induced bone metastasis is predominantly mediated by PARP2 in the myeloid lineage and less by PARP2 in the cancer cells.