PLK1 and rhabdomyosarcoma: We previously reported that PLK1 inhibitors and microtubule-interfering agents synergize to trigger apoptosis following prolonged mitotic arrest in ES, rhabdomyosarcoma (RMS) and neuroblastoma (NB) cells [13, 45–47], i.e. tumor entities that have been reported to overexpress PLK1 [11, 12].