Although XNC10’s ligands have not yet been identified, several lines of evidence are consistent with XNC10 representing a CD1 functional analog accommodating lipid antigens, namely its expression pattern, the invariant T cell subset that it restricts, its roles in antiviral and tumor immunity, and even 3D structural modeling, all which point toward a CD1d-like lipid-presenting function. The gene discussed is CD1D; the disease is neoplasm.