Transmembrane 4 L six family 1 (also known as L6 antigen, L6-Ag, TAL6, and L6) was initially identified in 1986 (Hellstrom et al., 1986b) and was a highly expressed surface protein of human lung, breast, colon, and ovarian carcinomas, which could be used as a cancer-specific antigen with the mouse monoclonal antibody L6 (mAb-L6) (Hellstrom et al., 1986a; Garkavij et al., 1995). The gene discussed is TM4SF1; the disease is ovarian carcinoma.