ROR1 and ovarian cancer: 34 Silencing of EMT transcription factors Snail and Slug induces chemosensitivity in A2780 cisplatin-resistant cells, while upregulation leads to radiotherapy resistance and chemoresistance in A4 ovarian cancer cells.11, 35 In our study, we found that simultaneous silencing of ROR1 and ROR2 significantly sensitised cells to cisplatin (Figure 6c), a commonly used chemotherapy agent for ovarian cancer patients.