It has been found that the levels of α3, α5, ß4, and α9 subunit mRNAs are significantly increased in SCLC (Improgo et al., 2010, 2013), and that the levels of α7, α9, and α10 subunit mRNA are also increased in a number of cell lines derived from SCLC and NSCLC tumors (Improgo et al., 2010). Here, IGKV6D-21 is linked to small cell lung carcinoma.