SF3B1 and B-cell chronic lymphocytic leukemia: SF3B1 is the most frequently mutated component of a spliceosome associated with diseases such as chronic lymphocytic leukemia (CLL), chronic myelomonocytic leukemia (CMML), myelodysplastic syndrome (MDS), and breast and pancreatic cancers [22,23,24,25,26,27,28] and is the best-known drug target in spliceosomes [28].