PROM1 and neoplasm: In particular, miR-216b, a well-known tumor and metastasis suppressor mi-RNA, that targets Ras [43,44], was highly expressed in prom1-exo and undetectable in FEMX-I cells, indicating a detoxification role for prom1-exo; let-7i, associated with metastatic progression [45-47], was found to be expressed at levels 53-fold higher in prom1-exo than in FEMX-I cells.