Given that PARP1 inhibitors (PARPi) are currently used clinically for treating ovarian and metastatic breast cancers [27,28], and PARP inhibition results in the radiosensitisation of HPV/p16-positive HNSCC cells [21,29], we also aimed to determine the combined effects of Syk and PARP inhibition. This evidence concerns the gene PARP1 and breast cancer.