Interestingly, in contrast to the control ApcNN teratomas which did not express any neuroectodermal marker (0/20 analyzed teratomas), approximately 50% of all teratomas generated from different Tcf3 over-expressing ES clones were positive for the same set of markers (6/10, 6/10, and 4/10 teratomas originated from clones 1, 2 and 3, respectively)(Figure 4). The gene discussed is TCF3; the disease is teratoma.