TNFSF13B and acute lymphoblastic leukemia: We observed BAFF-system spliced isoforms in B-ALL cells, including a TACI isoform (GenBank AY302137), APRIL-β (NM_172087), APRIL-γ (NM_172088), and the newly identified APRIL-δ and APRIL-ε (GenBank DQ149579 and EF211088, respectively).