Presentation of tumour H-Y antigens to CD4+ and CD8+ T cells can be measured using H-Y-specific T cells from transgenic mice expressing a single TCR recognizing I-Ab-Dby [Marilyn mice (Lantz et al, 2000)], or Db-Uty [MataHari mice (Valujskikh et al, 2002)], respectively. The gene discussed is FUT1; the disease is neoplasm.