PML and cancer: Representing the so far broadest and most specific evidence for circRNAs in cancer biology, a recent study has identified that a number of cancer-specific circRNAs arose from a process central to many cancers [178]: certain chromosome translocations or other genome rearrangements are known to occur recurrently in cancers, such as leukemic PML/RARα and MLL/AF9 translocations, as well as EWSR1/FLI1 and EML4/ALK1 translocations in solid tumors (Ewing sarcoma and lung cancer, respectively).