JCHAIN and breast cancer: The abundance of immunoglobulin J chain (IGJ) is significantly higher in CRC mice than in control mice (71).IGJ can predict outcome and relapse in paediatric pre-B acute lymphoblastic leukaemia (72).The expression level of IGJ was downregulated in esophageal cancer (73).IGJ was downregulated during breast cancer progression in tumor-associated stroma (74).