In vitro-cultivated, tumor-infiltrating B cells (TIBs) from non-small cell lung cancer (NSCLC)—which commonly harbors KRAS and EGFR mutations (3)–are able to present antigen to and activate CD4 TIL, while some TIB subsets can have an equally immunosuppressive effect on CD4+ T cells (15). The gene discussed is KRAS; the disease is non-small cell lung carcinoma.