While free MMAE indiscriminately radiosensitized independent of tumor receptor status, antibody conjugation specified MMAE radiosensitization to target-receptor enriched tumors, i.e. cetuximab conjugated MMAE radiosensitized EGFR expressing but not EGFR negative cancer cells while trastuzumab conjugated MMAE radiosensitized HER2 expressing but not HER2 negative cancer cells50. Here, ERBB2 is linked to cancer.