The tumors from the NIC-GLUT1F/+ mouse expressed Cre and GLUT1 (Fig. 2), suggesting that, in this mouse, Slc2a1 haplo-insufficiency did not occur, and that there may have been early changes in tumor metabolism that overcame the loss of one Slc2a1 allele. The gene discussed is SLC2A1; the disease is neoplasm.