Wang et al. observed a unique IGKV4-1/IGKJ3 rearrangement pattern in Igκ light chains from multiple cancer cell lines, including HT-29 (colon cancer), A549 (lung cancer), HepG2 (hepatocellular carcinoma), HeLa MR (cervical cancer), and U2OS (osteosarcoma). The gene discussed is IGKJ3; the disease is colonic neoplasm.