NANOG and combined immunodeficiency: To determine whether the upregulated NANOG in AI tumors is required for CRPC growth, we employed two lentiviral short interfering RNA vectors, that is, LL-Nanog and TRC (targeting 3′-untranslated region and coding region, respectively [3]), to knock down NANOG in LAPC4 and LAPC9 AI cells, which were then implanted back into castrated NOD/SCID (nonobese diabetic/severe combined immunodeficiency) mice.